In order to use the 3650 in a 97 you need a 3650 clutch and flywheel. Easiest way to tell is either get under there and look. 3650 will be beefier and typically be tagged tremec. Also look at the door code.
it was a 'direct bolt in'?
Just put a t3650 and an 03 mach 1 engine into my 98gt, the cross memeber needs to be notched out to fit the t3650 however, some people say they have had vibration problems due to not notching the proper angle. I am going to try the crossmember for a t3650 and see if it mounts to the 98