Hello.  I have a 1940's CAT 12 Road Grader.  There is currently a pony motor in the machine but has been drilled out for a starter.  I am unable to figure out what starter needs to be purchased and installed.  Local mechanics just don't remember.  Does anyone on this forum have some information on determining the correct starter?  This is a grader that has occasional use on the gfarm.  Let me know if any other information is needed.  Thanks in advance.

Delco Remy 40mt or 42mt but you will need to fit a helical gear to the starter to match the flywheel.
Old Magnet is the guru on most things but especially starters and he will hopefully be able to confirm the requirements including number of teeth and rotation direction.

There are no commercially manufactured starters for the conversion. All are mostly modified 40MT or 42MT and 50MT's are possible. The best fit is had using the correct 12 hole lever housing, the special drive end housing and the eleven (or twelve) tooth RH helical drive as applies to the D4 and D6 (not D6B). For early tractors with no glow plugs I'd recommend the 12V version for convenience when jump starting. 24V units are for use with glow plugs.
Here's one option....www.ebay.com/itm/225143635558
 

Thanks OM... BTW, many of us looked for you at John P's BBQ this weekend, you missed out on some good eats. Hope all is well. JM