if this is the wrong section or improper for the site in general please remove.

my 4l60e is living by pure miracle right now, it functions properly but is in no way healthy. question is i can pick up an 80e and tcase fairly cheap(its a crapshoot if its any good i now) but its something ive always looked into swapping to in general so i have some qestions ive yet to find answers to.

1) Im terrible with wiring, are their differences between years of 4l80E's like their are certain years of 4l60es? this would be going in a 94 so im not to sure what wiring in eed to change or add, i know once wirings done i can add the 4l80e specs into my tune instead of the 60e trans specs.

2) Im told that theres a minimal 1mpg loss from going to the 80e? any truth behind that? my truck is tuned well but shes gotten really tired over the last year, my goal was to use the motor i just rebuilt and swap it in, find another 60e and use the spare case i have since that was redone and low mileage in general as well, but finding a 93-94 60e in any decent shape is hard im finding.

3) Overall dimension difference, how much longer will the 80e setup be? Its a 93 2 door yukon, 6" lift, not at all cranked 3" block in rear(for now) i built a proper driveshaft for it awhile back when i worked at CCI Driveline so too much longer and ill be bottoming out at ride height. That can be solved by a bit of crank and a 4" block which once again would be temporary, until i feel like dropping tank for drop hangers and my d44 up front

4) 80es share the same spline output as a NV35/4500 correct? so one of those should mate up if i cant find an manual shift case behind the 80e already?