Are gt5 and gt4 rear ends interchangeable?

[Domes68]

I have a 2005 Sierra 1500 with a blown gt5/g80 and a 2004 Silverado 1500 parts truck with a gt4. Just wondering if everything would be the same if I were to swap them or not

[SierraHD17]

Gt5 is 4.10 gears and gt4 is 3.73... so if you have a 4x4 your gear ratios won't match rendering 4 wheel drive useless and the the speedo and shift points will be about 15% out because of the gear change.  

 

So.in short unless this is a 2wd truck and you want to tune it after...no.

[Tressa Kirchner]

Would I be able to switch out a gt4 rear end with a gt5 rear end if I had the the transfer case & front end from a gt5 drive train?

[CamGTP]

The transfer case makes no difference. Just the front and rear diff must have matching gear ratio's so things spin at the same speed.

 

You will want to re-calibrate the computer for these changes as well because the shift points and speedo will be thrown out of whack with a gear change like that.

Edited August 12, 2021 by CamGTP