when i originally bought my 85 it came with an extra engine that the owners did not what was. The front, mid, and rear irons are stamped r5-r-r5 which according to the atkins sheet are 12a #s. the front iron is stamped "B67897". the rotor housings are 13b housings, and the front rotor housing is stamped "r41" and "B51396". is this just 13b rotor housings on 12a plates, or is there a better way to id engine parts.

 

I don't know the side housing codes by heart, *but* te '74-78 13Bs used the same side housings as 12As of the same year.