I think this is a 1936 - SN 203590

I am learning that finding parts is difficult and a bit discouraging.  I could use a little help.

I am looking for a water pump or the parts to rebuild mine.  

Muffler - all ads say for 1938 and newer.  Suggestions

Belts - Do they cross with common belts?

How do I determine which carb I have so I can buy the right rebuild kit?

Greg