Mjr. Crash, unless you are really set on the manual application, I would avoid it. I have gone through a lot of trouble to be able to put a manual transmission behind the 500 slated for my pickup. Although it isn't insurmountable, it can be expensive. Here is why:
1. Cadillac motors of this vintage (368-425-472-500) never came with a manual transission. Consequently, they were never drilled for a pilot bearing. There is a person on the MTS web page that can help you with this, he makes custom pilot bearings, and has instructions on how to drill the crankshaft. This can be done without tearing down the motor to get the crankshaft out. His name is Caddycarlo, he has his own website.
2. For the same reason as above, there were never any manual flywheels built for this motor series. Custom flywheels are available through MTS, but current pricing is $350.
3. A cadillac motor requires a BUICK bellhousing to be able to bolt up a starter. Buick and cadillac have the starter on the passenger side of the motor, the same as chevy. Pontiac and Olds have the starter on the opposite (drivers) side of the motor. If you get a bellhousing from a pontiac or olds motor, make sure that it has the dual pattern for a starter on either side of the motor.
4. There are also two main types of input bearing diameters on the bellhousings available for this swap. Make sure to get the correct type for the transmission that you intend to run.
