In Reply to: NOS 8n block posted by JOSH in RI on December 18, 2020 at 21:29:19:
8N-6010-C is the part number for the block assembly after 1950. It wouldn't be marked anywhere on the engine. Does it have the front mount or side mount distributor? Your "c623" number is not a serial number. Where are you seeing that? Serial number would be hand stamped on a boss near oil filter housing. Block starter pocket would have a DATE CODE ID tag, cast on the block at the time it was poured. Can you provide pictures?
FORD ENGINE BLOCK SERIAL NUMBER HAND STAMPS:
FORD N-SERIES TRACTOR ENGINE BLOCK SERIAL NUMBER LOCATION:
EARLY 8N ENGINE CASTING DATE CODE BOSS, SEPTEMBER 16, 1947: