On the bottom of the pan rail it is clean with no Machining Number or Assembly Number or year Identification Letter, i would be looking for the rivit or the rivit hole to see if it was a Warrenty Block. No Year Identification on the top pad also make one thing to look for the rivit or rivit hole.
In the picture above you see the rivet, a joy to find that. I just stuck a extra blue tag, I had laying around, there for reference.
A gentleman who worked at the St Louis plant claimed the factory recalled and replaced all the early bad main cap Hemi‘s poured in early 65 (August). My car has a shipping date of Jan 66 (before the new batch Hemi’s where built) so this engine would be a perfect fit. Can’t prove anything but makes me satisfied.
