L31MaxExpress
I'm Awesome
I had to swap the flexplate, rebuild a crossmember, swap the shift cable, extend and rewire the transmission end of the harness, segment swap in a 4L80E transmission tune, and changed to the later 4L80E cooler lines when I swapped my 97 Express to a 4L85E. It was well worth it. I had the driveshaft swapped to the shorter 4L80E yoke and rebalanced. My LKQ sourced 110K mile $650 4L85E is still shifting well and handling the 383s power. The worst part of the crossmember modification was choosing where to cut it on the RH side to clear the GM dual 3" pipes to the muffler. It gets tight where the pipes go over the OE crossmember. I cut the crossmember into 3 parts and moved the transmission mount point back with 1/4" plate steel. On my 99 Tahoe that was easier, just slid the crossmember back and drilled 2 new holes. The front 2 holes actually lined up to the OE rear holes.
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
Last edited:
