[Held for Ransom]

Originally Posted by SD455DJ

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

They would be dated I043 and I063 which would be Sept 4th and 6th, 1973, making them '74 heads. Now they could be 46 (350) or 4X (400 or 455) heads, found on the center port. And the R45TS would point to the 400/455 head (350 used the R46TS plugs).