Big Pop:
RPO (regular production option) 317 is the powerglide transmission option. This option also included the 235 engine with hydraulic lifters. The regular car engine was a 216. This 235 is a "bad" one, with babbitt bearings and low oil pressure. How does your head say 216? Did you check the casting #?
Mario:
The J suffix in your engine serial number is for a '57-'62 Thriftmaster 235 backed by a 3-speed tranny. The J engine was used in the '57 34,35,3700 series, the '58-'59 31,32,36,3800 series, and the '60-'62 C10-20-30 series trucks. The casting date code on the block would pinpoint the year. Going by the format of the serial number, it's a pre-'60. I would guess a '58 or '59. Yours was built on May 30 (530) at the Flint plant.
