[SD455DJ]

Originally Posted by jciwolf

Can't find any numbers on either head, only numbers are 1043 and 1063 right and left plus the gm3 on both. If there are more than that it would have to be further up on the heads and no offense I don't want to pull the covers. Any other ideas would be welcome. jciwolf

jciwolf, those are the date codes on the heads, so cast January 4 and 6, 1973 which will point to 4x castings with 2.11/1.66 valves, possibly with screw-in rocker studs, and have 98 cc chambers. These were the standard head on the 400 4-bbl engines for 1973. On the left cast boss next to the valve cover there should be a stamp of 3, 3H, 4, or 4H (most likely 3/3H for the 73 castings).

Dennis