hey, it's lookin great i am currently doing a L20b in my 71, just a quick thought are you goingto be putting in a pointless dist.?

I am running a 1980 720 L20B Matchbox Ditributor & Coil. My opinion this is the only distributor to run, the matchbox.

My sugesstion is to get the coil, distibutor, and the wiring from the distributor to the coil with mounting bracket (new coil is larger in diameter). This makes it easy to install. You take out the old coil & ballast resistor. The wire that goes to the ballast resistor from the ignition switch will now connect to the new coil + terminal. When you get the Matcbox distributor & parts leave the wires conected to the coil. This makes the insall easier.

yeah, i was runnning that when i first got the engiine in but quickly swaped over to pointless, it was actually really easy and cheap!

Front Disk Brakes with Vented Rotors are now installed.

Left Front



Right Front



Stock 14” Wheel on the front Disk Brakes. A huge thank you to Mike Klotz for designing such a great bracket and the spindle sleeves so I could use the standard 720 inner & outer wheel bearings. This was an incredible easy upgrade.



No problems finding wheel bearings for me.

I also used a 50 amp 720 internally regulated alternator for now. I still had to grind the top of my pitman arm a little for clearance.

I picked up a homemade AC compressor bracket off of a 1977 620 that I am using as a starting point for a custom bracket.

I will post pictures of the alternator & AC bracket later.

I also modded a 1986 Honda Prelude Radiator in but I have concerns of it cooling my L20B properly. I will be designing & installing a custom aluminum radiator in the near future.

Next will be rear end gear ratio change & rear drum brakes rebuild. Original plans were to do rear disk brakes but until I get a job these are going to wait.

I installed a 1980 Datsun 720 rearend in my 520. The 1980 720 rearend is 7/8” wider on each side for a total of 1 ¾” overall increase in with. The measurements were taken from WMS to WMS (Wheel Mounting Surface). The other difference is the hydraulic brake hose is on the passenger side. I also used the 1980 720 rear spring shackles & bushings as the 520 bushings were bad. The 720 shackle bolts are a smaller diameter than the original 520 shackle bolts. The 720 shackles are about ¾” longer than the 520 shackles.

I notched the cross member for the transmission mount and built a custom bracket utilizing a stock 1980 720 5 speed transmission mount on my 3N71B automatic transmission. Pictures will be included when I finish all the welding.

I am sending my 1980 Datsun 720 driveline to Mountain Drivelines (formerly d!ck Driveshafts Phoenix) to have it shortened & rebalanced. I have had d!ck doing my drivelines since the early 70’s. This man is a wizard when it comes to drivelines.

Mountain Driveline
1560 E Lumbermens Loops
Show Low Arizona 85901
(928) 532-8452 d!ck Brown

I removed my tail lights for cleaning & repair. The passenger side tail light housing is rusted out on the base of the reflector. So I am considering doing this when I get a job.

Here is a custom rear roll pan that I would like to build in the future for my truck.



This will be an expensive piece when it is completed. All the lights will be LED & the turn signal lights will be sequential. These lights will be flush mount with custom billet bezels. I estimate total cost of roll pan fabrication at about $1200.

Hey Charlie! New guy on the block. Looking for wiring harness for 1970 521 with L20B and 5 speed.Also interested in electronic ign,and disk breakes. Would appreciate any help I can get. Thanks Ty.

I finished the front suspension & front brakes. Changed oil pan & pickup tube. Installed new u-joints. removed fuel tank & sender, sender is shot. Painted the bottom back half of the frame & tank brackets. Set cab on 4" blocks in preparation of cutting the tunnel & firewall out. Installed Cannon intake, Weber, thermostat housing. Cleaned up all 11 of my hub caps. I will sell off the best set for know to buy fuel gauge sending unit. I will also be selling a set of bumperettes with brackets. I will post pictures this weekend after I get my camera repaired.

I have started on the custom wiring harness. Here I am stripping out unneeded circuits of a 1985 720 4x4 king cab harness. Main circuits kept from this harness will be the charging & power windows & power door locks. Ignition & lighting circuits will come from a 1980 720 regular cab 2 wheel drive 5 speed harness. The inhibitor (automatic transmission) & heating/AC circuits will come from a 1985 720 2 wheel drive regular cab pickup. Not sure if I want the seat belt warning buzzer as I find them annoying.

This is the 1985 720 4x4 king cab harness.



Here is Princess Buttercup guarding some of the other harnesses.



She has a mean tail whip just ask Pepper our Great Dane & the 3 cats.

Princess Buttercup enjoys here days chasing the cats in the back yard.

Today I cut the firewall out & laid out the piece to weld back in.

I will be using a 620 pedal assembly, power booster, & master cylinder. I have disk brakes on the front thanks to Mike Klotz's talents.

The main reason for the new firewall is engine clearance. Right now I have the cab sitting on 2" blocks on the stock cab mounts. I will have to clearance the tunnel also in order to remove the 2" blocks. I want the cab at stock height off the frame.

On the flange that I drilled the spot welds out of, I plan on bending an angle on the new firewall to match the flange with the holes in it and the spot weld the 2 pieces together then grind welds smooth.

On the bottom of the cab as well as all around the cut out, I will drill 1/4" holes in the original floor spaced 3" apart to spot weld the new firewall flange to. Everything will get seam sealed when all the grinding & welding are finished.

The replacement firewall will be a nice flat surface with only holes that are necessary.

New firewall cut to ruff outside dimensions.


Prepping the top ridge for firewall removal.







I tried to cut just under the bottom ridge to remove the entire flange. The new firewall will be bent to lay with the original floor. The new firewall will have a 1” underlay of the original floor that will be spot welded every 3” and seam sealed.

More cut out pictures.





More this weekend.

I cut the transmission tunnel out today, and my brother is trimming and bending the firewall should have it back next weekend and get it installed. After the firewall is installed then he will make the 2 pieces to do the tunnel. The tunnel & firewall are made from 16 gauge plate, much thicker than the original 22 gauge the original fire wall & tunnel. The tunnel will be flat on top instead of dipping down like the original tunnel.















The cab is bolted down without the 2” blocks so this will be the height of the cab off of the frame. It is sitting on all new OEM NOS bushings. These bushings are not the original 520 bushings and are ¼” thicker than the originals, but they are Nissan bushings (isolators).

Here is what I did today on my truck.


Passenger side of the new firewall.


Another angle from the passenger side.


Recessed detail from the drivers side. Ia m bending the old metal down over new firewall. I will drill holes in the old metal to spot (plug) weld to new metal. After all the fitting & welding is done all joints will get a coat of seam filler.


Another angle of the cowl drain detail showing the old metal being folded down to weld to the ne firewall.


Drivers side new firewall.


Inside cab drivers side firewall.


Inside cab center of firewall.


Inside cab passenger side of firewall.


Comparing old cowl drain to new cow drain. Much lager than the old one. But remember I live in the desert.


Another shot of the old cowl drain. I plan on going back with a simimlar but larger system.

By the way I have the valve vover on during all work. Tomorrow I am going to pull the motor and trans loose from the mounts & move it forward as far as I can get get more room to work on the cowl drain area.

It sure has been a long time getting here.

I am looking into the possibility of replacing my 520 transmission mount, torsion bar, & emergency brake cable mounting crossmembers and also replacing torsion bars & mounts.



I am looking at the 620 & 720 as possible donors. The reason for these changes are easier installation & removal of transmission due to having a removable crossmember. I am running a 620 emergency brake handle assembly & 720 emergency brake cables & rear differential housing & brakes this will enable easier installation & marrying of the different parts.

that firewall looks great, i did mine almost the same but i recessed it back even farther for the bigger engine. love the truck keep the pics coming lol

Thanks 67 411 I appreciate the feedback and any ideas that might make this even a cleaner install. I heard a rumor that you are getting a tig. Congrats man that is almost equivilant to a first born.

Charlie69 wrote:Thanks 67 411 I appreciate the feedback and any ideas that might make this even a cleaner install. I heard a rumor that you are getting a tig. Congrats man that is almost equivilant to a first born.

lol dont know about it being like the first born but i can say it cost less lol. I am getting a cheep tig it will only do stainless or regular steel. Your install looks real clean, on my truck im trying to find a way tho hide the clutch and brake master cylinders under the dash or floor. keep up the updates and pics this stuff is what makes my day

I received 2 of the 3 tunnel pieces from my brother. He tacked them in and the next morning I went out & started measuring & eyeballing and relized how crooked they were, so I cut them out. I also noticed that the 1980 720 heater box was going to be to high for mounting because the front (firewall) end of the tunnel is 3/4" to high. Any way this pissed my brother off so now it is the hurry up & wait game with him again.

Tired of waiting on my brother so I went and mocked up the tunnel pieces. I decided to split the second piece in half because the front was to narrow & the back was to wide. I tack welded the front & middle tunnel pieces together mocked them up in place and realized that I need to do the same with the front piece of the tunnel. So tomorrow I will split the front tunnel piece and fit it to the openning. Once I finish this adjustment I will do the filling in where I need to and this weekend I hope to be able to finish all the welding I can with the cab in place. The next weekend after I will pull the cab off the chassis and finish all the welding & grinding from underneath & the engine compartment. Finish, prime, & paint the inside of the cab & the engine bay.

While the cab is off the chassis I plan on cutting out the center (transmission mount) cross member & the remove the torsion bar crossmember from my frame & then fit & weld in the cross members from a 1974 620 frame if all measures up like it looks to.

I am contemplating doing coilovers in the front and doing away with the torsion bars all together. If I do coilovers it will be like syclone916 did on his 520.

If I do the coilovers it will cost about $250 more than doing the 620 torsion bar swap.

Gene (dat521) came over today and between the 2 of us we managed to pull the windshield out without breaking it & without destroying the weatherstripping.

I took the windshield from my 1966 520 and laid it on top off a 521 windshield I have. They are the same. I have been told by 3 different people the my 66 windshield would be about 1" narrower side to side than a 521. So this is proof to me they are the same.

The transmission tunnel is in!!!! Do some grinding & pull the cab to finish the welding & grinding, primer & paint the bottom & in the engine compartment.







It is getting closer to being done. Yaeh!

wow that trans tunnel looks great! I was wondering (Hopefully you didnt say and i missed it) are you going to smothe stuff under the hood or just leave it? You are making great progress, and thanks for all the pics. Keep up the good work, cant wait to see what you do next.

Thanks for the encouragement. I hope to smooth every thing I can. I have a lot of grinding work a little bondo & primer & paint I am happy with the results of the tunnel.

I work on grinding and spotting some of the holes that appeared. another day of grinding should have it ready to puul the cab to finnish firewall & undre the tunnel.

Well I have been grinding down welds. I got bored grinding welds so I have been working on the heater AC assembly. I have also fit the brake pedal assembly, emergency brake handle assembly & throttle pedal & kick down switch.

Here are pictures of the heater & AC assemblies. The heater & AC are from a 1980 720 and the controls are centered with the radio hole in the dash. I still have the duct work to do. I need to install my wiper assembly to besure the new ducting clears the mechanism.

I received my power window hardware from PEZi720. I already have the power locks. All Datsun/Nissan parts except radiator & fans. I installed the radiator will order 2 12" fans tomorrow.

I have the pedals emergency brake handle apart waiting for paint to dry before reassembly.

Here are a couple of pictures of the progress.

looking better and better man, i wish mine still looked like a truck lol. Grinding sucks but it makes it all smooth and shiny lol. Always love seing your updates great work.

Thank you 67411 I appreciate all feedback.

Does any one know what a safe operating temperature range for 3N71B automatic transmission is?

Has any one had any experience with this type of cooler?



http://www.summitracing.com/parts/DER-13262/

I am thinking of installing one of these on the front of my frame rail under the radiator behind the apron.

can't say i know the proper operating temp... but a cooler can never really hurt... haven't yet had time to look into which type cooler i will be using come that time either, so i have no reviews to offer
p.s. i'm sorry i haven't gotten back to you on the measurements for the windows! will do either sunday or monday!

I did this a while back but I forgot to include it. Modded radiator support frame toget more room for radiator & AC condenser.

Great project! Keep up the good work.

Thank you! I have been at it for a little over 2 years now. Slow & easy I think will win this race.

My most challenging metal fab is still a head. Replacing the fresh air intake, I had to cut it out to get the heater defroster plumbed. It will have several opposing angles whatever that means. LOL

In the process of customizing a 1980 720 column, turn signal switch, wiper switch, ignition switch, & plastic clam shell to work with my stock 66 520 steering wheel & horn button not to mention the all ready modified steering gear box. I have to have intermittent wipers. Pictures to follow.

Well I have made some progress I spent the last week working on a 1984 720 tilt column install. I hope to finish it tomorrow. I have been working on the wiring. I decided to run a 1980 720 2WD king cab automatic wiring harness. I have the wiring done for the 520 instrument cluster to the 720 harness. 2 wires to shorten up tomorrow when I get some connectors and the instrument cluster will be plug and play. I bench tested all my work with a multi meter first and then I hooked up individual circuits to a 12volt power supply and tested each with power. No smoke so far.













Wiring takes a lot of time. It is definitely something you cannot hurry.

A big thanks to Wayno on Ratsun for his imput on this mod. He has done 3 or four of these. He is the one on Ratsun that king cabbed a 521 last summer and is currently finishing up a 520 king cab. He also purchased Mike Klotz's NL and has it all painted and looking like new.

ugh... wiring... not thrilled to do mine

Here is the finished gauge cluster with the 1980 720 harness connected.