how to tell z32 from a j30 diff from the outside?

[SketchyRollin564]

After a painful year of open diff, i just recently swapped to a J30 diff. Besides having power to both wheels, i was also excited about having the slightly taller final drive. (its roughly 4% taller). It should lower the cruising RPM in 5th gear (since we all know how horrible our 5th gears are on the highway), and also, allowing me to stay in each gear slightly longer, since i have an SR with a KA transmission (way closer gear ratios), and i feel like i have to shift after every 3 seconds if im going through the gears at WOT

I know its not a huge difference, but i remember when i put a J30 in my old s14 (stock KA), i noticed a slight difference in between geras, and it made 5th gear a little easier on the highway. Also a bit slower with lack of power, but wasnt too bad

My current s13 has an SR with upgraded fuel pump and few bolt ons on 12psi, so its obviously making a good amount more power than a stock KA. This is why i wanted/needed the taller final drive from the diff, considering im still using the KA transmission with the midget gear ratios. However, when i put the diff in, i didnt really notice a difference at all. What makes it harder to tell is that my speed sensor wires are messed up, and i havnt gotten around to fixing them, so i cant compare what the speedometer read before and after.

My friend had a GPS app on his phone and according to that, 5th gear at 2.25k rpm was 45mph, 2.5k was 50, and 3k rpm was exactly 60mph. Top of 4th gear was only 100

For my friends with SR transmissions, 2.7k in 5th is 65mph, 3.5k is roughly 75/80, and top of 3rd gear is just a hair under 100.

Anyways, aside from all that, i feel like my final drive didn't change at all, but im trying to figure out if its too minimal to notice with more power, or i have a 300zx diff instead

I know its not a 240sx vlsd because its 5 bolt. I traded engine mounts to my friend for the diff + axles (came with his car) because he wanted to go welded, and i wanted to go vlsd, so it worked out.

As far as i know, both J30 and Z32 diffs have the ABS sensor on the tail end of the diff where it meets the driveshaft. However apparently some z32 diffs have ABS sensors on the output shafts?

The only way i know of to tell which diff is which is to open it up and count the teeth, or find the stamp with the final drive. I really dont want to do this since the diff is already bolted up in the car, and i dont have a garage at my apartment to do any work.

Does anyone know of any way i can tell which car the differential is from without opening it up? Any other markings or differences

thanks in advance

[Cody240]

All j30 diffs have the abs sensor on the snout of the diff (making them 3/4 of an inch longer than the normal 240 or NA z Diff) and all NA z32 diffs have the abs sensors on the output shafts (which makes them the exact same length as the 240 diff)

[SketchyRollin564]

All j30 diffs have the abs sensor on the snout of the diff (making them 3/4 of an inch longer than the normal 240 or NA z Diff) and all NA z32 diffs have the abs sensors on the output shafts (which makes them the exact same length as the 240 diff)

i know that some n/a z32 diffs have the ABS sensor on the outside, but are you sure its ALL of them? Cause as far as i know, the ones with ABS sensors wont work in a 240 unless you change the half shafts, since they are too wide, and ive heard of people bolting in z32 diffs directly in with no problems

[Cody240]

Well i have done several 300zx diff swaps into 240's and each 300z diff i got had the abs sensors on the out put shafts. and yes in order to swap in a z diff into an s13 you need 92- 94 j30 axles and swap the cover from the 240 diff. i dont know about the s14 though.

[AZhitman]

You can tell the ratio by turning the input shaft and counting wheel revolutions.