I may be about to buy a 91 240sx SE with an A/T. I want to put a M/T in it. but i don't know if its an semi easy swap or is it a pain in the *** kinda swap. i want the gear ratios of the a/t but i want the control of the m/t

 

Well, if you swap the transmissions you have to realize that the M/T is going to give you the M/T gear ratios, and the auto will give you it's gear ratios. They're intrinsic to the transmission gearbox. The swap could probably be done without too much hangup, since the car is RWD. But what I recommend, and what most people would, is trying to simply buy the car with the 5-speed from the factory.