Projects To a T- Trevor's T-on-A RPU

Those 42-47 truck open rears will most likely be 3.78. All the ones I've had, been that ratio. Look on the center housing there will be two sets of numbers stamped on the ridge running parallel to the pinion, divide those and it will give you the ratio. Provided no one has changed the ring and pinion.

 

It will be pretty happy with 3.78s too (75 at 2500 in overdrive). Thanks for the tip on IDing them.

 

If you like, I can take a picture of where the numbers are. I have one mocked up in my roadster right now. It has 3.78 and a T5 behind a hot flathead. I have a Camaro T5 that I swapped the top plate and tailshaft housing of a S10 T5 on to it so I could has a 2.95 first gear ratio.