I have a 2001 mustang and I want to drop a new crate motor in it. what is a good motor to get?

It depends. Do you want to stay OHC? If so, I would recommend a 4V of some sort. You could get a Mach 1 motor, SC Cobra motor, or if you have the bank, you could get a FRPP 5.0 "cammer" 4V. What are you looking for?

Im looking for a motor I can just drop in. Im not looking for a hellacious motor just something close to the stock GT V8.

Well, if you are going to put a new motor in it, I don't see any reason why I would stick with a 2V. Maybe just look into a N/A 4V crate motor. I think www.karkraft.com usually has some posted up.