RB25 to S14 swap...gearbox options

[pirate87]

Ok guys here's my dilemma:

I'm also going to preemptively apologize for running this question into the ground, but upon searching I have only come up with loose and scattered information on the topic.

Basically I ordered my engine set (S1 RB25DET), but when the importer inspected it prior to shipping, they found that the gearbox was bad. The motor checked out fine so I made the decision to have them send it to me anyway. Now, however I am stuck without a gearbox. I dont want to pay $1300 to buy one from Mckinney, but I am having the worst time even finding another for sale.

I have read that the RB20DET transmission can be used, but is not ideal due to weaker components. I may have to go this route, just because they are much easier to be had. Will this gearbox bolt directly up to my motor? And, how's the fitment differnent from the RB25DET gearbox?

Also, I have read that the NA 300zx transmission can be used. Does the bell housing need to be interchanged with the RB bell housing?

Basically, I just need some expert opinions on this matter. I know plenty of you have been through similar situations, so I'm just going to soak up all the advice you guys can give me. What would you do in my situation? Thanks!

[S14-NEO]

yes the 300zx internals will work just fine in the RB transmission ...even better news i have one if you need it (300zx transmission)

[Chaos the Xile]

Not to be a post jacker, but does the 300ZX transmission have to be N/A or can you use the TT transmission and parts as well?

[pirate87]

TT parts will work, but the clutch is slightly bigger than the NA clutch.

Unfortunately, I don't think a 300zx transmission would work as I do not have an RB25 bell housing.

[Chaos the Xile]

ok but as far as the synchro go... the over all internals, which would be better for use. TT or N/A?

[pirate87]

the internals are the exact same, so ideally you would use the NA transmission so the fit is better