I just got my fix-er-upper 'vert last night, and I have a non-running engine swap candidate GTUs sitting in my driveway. Should I swap the 4.3s out of the GTUs and into the 'vert? I'm probably going LT1 or LS1 in the GTUs (keep the flaming to yourself, because whatever you say doesn't matter), and it's my understanding that the 3.9 rear-end from the 'vert is more desirable for that engine. So, the way I'm looking at it, the 'vert would be a little quicker with the 4.3, the GTUs would benefit from the 3.9. Sounds like a win-win.

My questions are: Will the rear end from my S4 'vert fit into the S5 GTUs, and vice versa? What else needs to be changed to go with it, or is it a simple swap?

 

from what i understand from reading on these forums all the na diffs, rearends and trannys are interchangeable.

 

Yes, it is interchangeable. You won't need to swap anything as both are 7 inch rear ends. Only trouble comes in when you try to put in a turbo rear and mix those parts.

 

I thought the GTUs rear end was a turbo rear.

 

No, it has the TII suspension, TII seats, TII Aero Mirrors, and sport/GS Aero parts, and a T2 Wing. Drivetrain was still N/A.

 

Ahh, cool beans. Thanks.

 

Also, unless your shooting for slower acceleration and better Hwy gas mileage the 3.9 is a bad choice. You'd be better off swapping in a 4.10 ring gear from another rx7.

 

No, the V8 has a lower redline and more torque down low, so having it spin slower is ok, and is better for highway driving.

I'm not so sure if you want a 7" diff with a V8 though, I'd rather have a 8" out of a TII, as it's stronger.

 

Yeah I missed the whole v8 part. definately want an 8 inch rear with that much torque. I think a v8 would snap that little n/a diff like a twig if you nailed it right.

 

no way the 7" from the n/a are actually pretty damn strong. they can handle from what ive researched before was up to i think 10's or even 9's in the 1/4 with no problem. but with the v8 even having more power you shoudl be fine

 

10's and 9's with what type of torque? I'm thinking that 400 ftlbs and a nice Pressureplate will break a halfshaft.

 

With a V8...or ANYTHING with more than 200ftlb's of torque...I'd want either a T2 rear/half shafts/driveshaft...or...a ford 8.8" solid rear. For a V8, I'd definitely go with a solid.

 

4.3 all the way, itll help make up for the weight

 

I broke an na open diff with 238 TQ. I powerbraked in first gear to finish off old tires. As soon as the clutch was all the way out and the boost came up the 3rd member broke just as the tires started spinning. It didn't matter to me because I had a T2 rear end waiting in the garage.