[AL in NY]

IMHO, the best swap of a modern transmission into a stock Model A is the Tremec RTS 4 speed with 4th being OD. This unit gives you a four gear synchromesh transmission with overdrive in 4th gear. This transmission is fitted in the Model A less it's tail shaft and therefore can be mounted in front of the frame cross member and brake cross shaft using a Model AA truck bell housing. The only real modification to the car itself is the drive shaft, torque tube and radius rods have to be shortened about 2 1/2". This transmission came in 84-87 Ford F150 2 wheel drive trucks with the L6 or small V8. If you feel you need a 5 speed, then more changes have to be done to the chassis and drive train because the transmission tail shaft cannot be eliminated. This means the frame cross member will have to be modified, the torque tube will have to be changed to an open drive shaft with universal joints. The Model A hollow radius rods will have to be replaced with something stronger that will absorb the rotational torque of the rear axle. And the mechanical brakes will have to be changed to juice brakes because the that rotational movement of the rear axle. If you would like the research the 4-speed OD transmission, search using "F150".