07 Silverado. Rear end stripped out, replaced now 4wd is messed up

Sirtomthegreat · December 2, 2016

2007 silverado classic 4x4. Rear differential went out, carrier bearing gave way and some of the roller bearings got caught in between the ring and pinion. Backed out of driveway and it shook and jumped up and down VIOLENTLY and VERY LOUDLY. Anyhow got the RPO number said was a 342 ratio. Bought a rebuilt 342 rear end installed and drove great until I engaged 4wd, could tell mismatched gears. Pulled cover on old rear end counted teeth ended up being a 323 ratio. Was a rebuilt truck that they obviously put another frame under with that trucks differentials. Took rear end back, installed a rebuilt 323, 4wd still feels mismatched. When engaged the front end feels restricted like the front diff is a lower gear ratio, or like the brakes are engaged. My question is this. I know the new rear gears are the same as the old rear diff. Is there a chance that when the original gears gave way, and it shook the truck so hard, or when the driveshaft was spinning a rear pinion that couldn't engage the ring, could it had messed a sensor up in the trans or transfer case that engages the front diff in correctly? Or could the wrong gear ratio in the first new diff messed up something in the sensors or ecm? I drove it about 20 miles before trying 4wd with the 342 rear end. I now know I have the correct gear ratio in it but the 4wd is not correct. Any help or suggestions are greatly appreciated.

Coby7 · December 2, 2016

RPO code for 3.23 is GU5, check your RPOs you may have a GW6

GU2 = 2.73

GU4 = 3.06

GU5 = 3.23

GW6 = 3.27

GU6 = 3.42

GU7 = 2.77

GU8 = 3.90

Sirtomthegreat · December 3, 2016

RPO was for 342. I physically counted the ring and pinion it's a 323. 2wd does great but when put in 4wd the ass end raises and the front end is like its stuck or something. When you put back in 2wd tension is released and the ass end goes back down.