I have a 1999 pontiac grand am w/ a 2.4, 4 cylinder.If i was to put a v6 in it what all would i have to chang

Changing the engine type is a bag of worms, not just in the work but getting it past inspection in this day and age. Basically, for anything since about 1984, anything other than the original type equipment is illegal under the federal clean air act.

First you need to make sure it will fit under the hood. Second, you may end up changing the motor mounts which would require some relocation. And you would also probably end up changing the transmission and the transmission mounts. Depending on where your steering is located, you may end up having to change it also.

A very big job, everything from transmission, mounts, wiring, computer, etc. Cheaper to sell the 4 cyl and buy a car with the 6.