While in the process of rebuilding my 1949 1/2 ton truck I found large chunks of metal (2 that were between 2 and 3 inches long and in a ring shape) in the bottom of the transmission. The transmission is a sm-420 of the 1949-1950 period(not sure of the year but the input shaft does not have the oil lip seal).

After opening the transmission it looks like the metal in the bottom is the second speed gear synchronizing ring retainer, as it is missing.

I was wondering if anyone had any suggestions of what could have caused the ring to fail and what other components I should investigate more closely as a result. Also is there cheap sources for these (are they a standard part?) besides going the Novak route?

Thanks for any comments/suggetions