There is also a stamped number on a lip at the front driver's side of the block. It says "4-83LC". I read this also to be a date code, i.e. 21st of March 1958. . .
Just wondering if anyone could help me decipher more of these numbers and also which one uniquely identifies the engine.
John, there are no numbers on many FoMoCo engines to uniquely identify them from all others, i.e. there are no engine "serial numbers" in many cases. "Numbers-matching Ford" generally means the date code on the engine predates the vehicle's scheduled assembly date by anywhere from a few days up to a month or more. The date on the engine is when the engine lower block was machined and assembled. It does *not* indicate when the final, fully assembled engine (with cylinder heads) was completed.
For instance I have an August 12, 1957 built Edsel that has a 1-77E7 date code on the engine block (July 5, 1957 at Cleveland number 1 plant), and one cylinder head with a casting date of 77Y (July 24, 1957) and the other with a casting date of 77D<inverted> (July 29, 1957). So one cylinder head was cast just a scant two weeks before the car itself was scheduled for assembly completion.
The date stamping you found, 4-83LC, indicates Lima, Ohio engine assembly plant (4), 1958 (8), March (3), 11th day of the month (L, because "I" was skipped). The final "C" is an internal inspection code.
Casting numbers only give information on the casting of the raw block before machining, so there is no way to, say, distinguish between a 383cid, a 410cid or a 430cid engine solely from the casting numbers.
The casting date on your engine block, 83C:1, is then March 3, 1958. The ":1" may indicate first shift. The 5751091 is the engineering number for the as-cast engine block. It doesn't translate out to a part number, because the engine block was not sold in that condition.
The number "11" is probably a mold identifier.
gauss