I can help in deciphering your truck serial number (H53S036680):
H=3100 series 1/2-ton.
53=model year 1953.
S=assembly plant=St. Louis.
036680=build sequence number beginning with 1001. This truck was number 35680 built at the St. Louis plant.
For a 1953 engine, the serial number prefix would begin with L. The J is for a 1951 engine, as JiMerit says (they went alphabetically). So JAC deciphers as:
J=1951
A=passenger car (I believe the 216 was the only one available for 51 passenger cars).
C=built at Flint plant with RPO 227 heavy duty clutch.
The rest of the engine serial number is the plant build sequence number, again beginning with 1001.
This engine info comes from a 1951 passenger car restoration pack, not the truck pack, but I believe it should apply here too. Somebody can correct me if I'm wrong.
