Thank youNo, you must replace it with a 3.6.
The 3.5 and 3.9 are totally different and will not function with the computer/wiring in the car. The 3.6 is specific to that model and computer/wiring.
ThanksThe LY7 was put in several cars.
GM High Feature engine - Wikipedia
You'd need to find one from another LY7 equipped vehicle, then swap over any brackets or whatever that is different. You will need to do a lot of research to make sure what else you may run into when swapping engines.