i found a 20b that was a c class and i tried looking up what the c class was. can anyone tell me anything on all the classes of the 20b. id really apreciate it!

drew

 

If you're refering to the 'C' series in the line of 20B motors then it's a good find. The major difference just by looking at the outside of the motor would be the larger casting in the dowel areas of the side (Iron) housings. The 'C' and later series are considered the stronger motors mainly for that reason.
Some more info in here--->

https://www.rx7club.com/20b-forum-95/what-20b-do-you-have-108091/