i have a 4L60E right now but was thinking about going to a 4L80E what all need changed for fitment or do you just throw it in?

 

4l80, hammer the floor since it's a little larger. you'll need your 99-02 tuned and a wiring harness, if it's a 98 you'll need a controller, manual valve body, or convert to 99 up PCM. You'll also need a 4l80 converter. It's my plan also, I might be missing something I'm sure peope will chime in, there are also better years to use than others, some of the old ones might not work? Idk don't quote me on that last part tho. This has been covered a good bit. Have you tried searching yet?

 

Lots of pain in the *** wiring when you don't even need an 80e really. Call RPM Transmissions up and get one of their built 4L60e trannys. They are bad ***! No wiring BS or cobbling your car up with a hammer. Screw that mess.

 

I have a 98 and my PCM is shifting this 4l80e I have......you just have to do some wire splicing and what not. you can use the stock 4l80 converter with an adapter or order one from Circle D....or any sponsor. The flywheel you need is the flat 6.0 with the adapter on it. do a search and find where to order it. I just got one for my other motor that will have a th350 for 55 bucks....
computer needs to be adjusted for the shifting points and delete a few codes. there is a lot of information on tech if you do a search for this.

98 CAN shift the Transmission. I know for a fact bc mine is doing it....
the PCM thinks its a 4l80 bc of some mods made to the harness.
good luck