beating this question to death! LT1/4L60E

[Church]

Man this is some awesome info in this post. I installed an lt-1/4l60e in an 88 Jeep YJ. My motor and trans came out of a 1996 Impala SS.
Some of these items were mentioned but I think they are worth mentioning again.

You will need to switch your inlet/outlets on the radiator. We bought a Be-cool Alum. radiator and switched the inlet & outlet ourselves.

Becareful with the vats on the newer vehicles (96 & up I think)
Vats is vehicle anti theft system. This thing can cause a MAJOR headache. Even with an aftermarket harness we had trouble with this. The chip on this went bad once. When this happened, the motor would turn over but not start for about 5 minutes, then it would finally run.

I heard these engines will run in LIMP mode, which basically means it will run but not give you the 300 hp it supposed to have.
Watch out for this. Also we had to get our comp. reprogrammed becuase we were running 39" tall tires with 5.39 gears. This really messes with the computer. It would switch to OD when the speedometer was reading 35mph. If you are running a tire that is about the same as what came on the orig. vehicle but are running a different gear, you might have to get the computer reprogrammed.

Make sure you get a fan that will cool enough. We had to switch from the perma-cool to the black magic even with the be-cool alum. radiator.

Lastly, Watch out for the waterpump and distributor on these engines. The LT-1 we had came out of a 96 Impala SS. When you have to go get a replacement, you better pull up a chair first. These things are outrageous!!