Pre-war (up to 1942) V12 engine changes

[JeffBp]

Can anyone tell me the changes to the V123 engines through the run. Specifically, 1933 to 1936? I have been told there were piston and ring changes? Any other?
And gearbox changes?

[Warren Rauch #4286]

      The question is a little to broad to answer. The best would be to go through the parts book line for line.
    Hollander Interchange manual lists Engines 31-35 and 36-37 as different. Cyl heads 31-early33 and late33-37 , connecting rods a change in pin diameter  in 1932.  The transmissions for all models 31-35, some to 37   basic the same ,but different main shafts ,clusters,  etc.And cases did change.

Reprint parts books are easy to get. It is what I would do.  Warren