Does anyone know where there is a resouce that will tell you what a 13B with R5 and 3B castings are from?

I guess I am looking for something that has all the casting codes, any ideas?
Thanks

 

No ideas, but 3B was '74-'75 RX-4 and REPU. There are two types of R5 castings, nitirided and non. Since nitriding didn't come out until '79, (or possibly '78), we can figure the nitrided R5 castings are newer than non nitrided R5 castings. My '76 Cosmo has non nitrided R5 castings.

 

Thanks Jeff!