Hi everyone, I have a 2012 suburban and am trying to figure out my transmission issue... It will shift and drive normally for about 15 to 20 minutes and then begin to slowly start slipping, if I stop and sit for 5 or so minutes it will drive and shift again for about 5 to 10 more minutes, it'll make a slight locking up feeling and clunk or bang but it feels like the front diff? I'm unsure. The Fluid is full, smells good and has good color... Not throwing any codes but an evap... Could this be a filter restriction once the fluid heats up and the particle in the filter heat and swell? Anyone ever have an issue similar to this, could it be a TCM reset or filter and fluid swap? Thank you all in advance for your help... I'm tight on cash these days due to becoming handicap from a motorcycle accident so I'd like to not throw good money away, I have an opportunity to get a 2 wheel drive 6L80 with low miles and was told I could cut the output shaft to size to fit the transfer case without any issue but obviously need a program.

 

Could I run a 4L60 or 4L80 in its place and if so, anyone know what it takes for the swap? Thanks