serial numbers Ford

[Adam33]

The following numbers came off of a 4600 that I am cosidering buying. Want to check the production date. can someone please help with decoding these numbers?
6L18B C521305

Thanks

 

[RickB]

6L18B is the unit code indicating a build date of Dec 18, 1976.
C521305 is the serial number indicating it was built in Highland Park Michigan and 1976 production.