i have 2 4l80es one is an 01 and the other an 02, the 01 has less miles, i have an 03 rcsb gmc, but it has been lowered in the rear, so will i need a different tail shaft or anything, and what else will i need? which trans should i go with, and will it plug right up? or does the harness need altering?

 

try checking out the sticky in this section..

 

sweet that helped with the wiring problem, now will i need to run a shortened drive shaft or different crossmember? anything or can i use all the stock stuff

 

good! im glad.. im tryin to get a MOD to rename the title cause i didnt name it right..

ok, you being a RCSB, i dont remember anybody posting up what they did..
me being a ECSB i didnt have to do anything with my factory DS.. just got all new UJoints and a TH400 Long Yoke put on it.. i trimmed off 5/8" and it fit perfect..

You being a 03? you should check out KYSilverado's write up he is doin on his Z71... same principle applies.. your goin to have to modifiy the xmember because the trans mount on the 80E is approx 6" further to the rear.

 

Bill renamed it for me...
Now it might actualy be noticable now..

 

man, this looks like its going to suck doing

 

Its not as bad as you think.
i did all my stuff in half a day and was in a hurry.. its still holding.. heck i put 1200 miles on my truck the weekend after the swap..

 

Is there anything wrong with the transminssions? Either of them?