I am about to do a wright up on one I did for a dealer that I did for him with a 3.8 he built with a supercharger on it. I think he is going to keep it.

ok so far every thing lined up for the 3.8 once the 3.5 was taken off of the engine cradle. the only thing had to be changed so far was the wires from the computer to the engine and the fuse box as well. the bcm didn't need to be changed out to be honest because we didn't change out the anti theft keys. so that saved time and work. other than that it was a little work for the harness for the engine to the rest of the wires in the car. majority had to be spliced into each other while one or two just needed to be modded to button it up. it just took about two weeks of down time. for the car just to make sure there was no supprises for the electrical.
other than that wish the monte carlos kept the 3.8 and have the 5.3 option