C5AZ-10A370-C Alternator mounting spacer, goes between the cylinder head and alternator housing. Fits 1968-70 390-2V, 390-4V, and 428CJ engines. Smog OK.
There is no casting number but one is listed C5AE-10A370-C. Inside diameter 7/16". We measure them out at 1-5/8 inches long, supposed to be pink anodized or tinted.