Want a new 904 for my 65 Cuda. Help!

Since your car has a floor shift, any later model trans would work. Does your current trans have the ball and trunnion rear flange, or does it have the slip yoke for a u-joint. If it has the B&T, you will need to have another driveshaft made to rid yourself of the B&T setup. Other than that, any 904 would be a bolt in and go. I would steer away from the later 70's lockup style though!! Hope this helps, Geof