(This page replaces the previous unverified Deciphering Your Ford Engine's ID Tag, which contains some pre-'65 data and is thus retained for research purposes only. The following data should be considered more accurate.)

NOTE: All numbers and specifications are as reported in the 1965-1972 Ford Car Master Parts Catalog.

All engines for 1965 and subsequent model years include an engine identification tag. This tag describes C.I.D., mode year, year and month of production, and change level number. On 8-cylinder 260 and 289 engines the tag is located under the water temperature sending unit. On the 8-cylinder 390 Thunderbird engine it is located under the left front intake manifold attaching bolt. On all other engines the tag is located under the ignition coil attaching bolt. All engine code numbers consist of a basic number, a suffix, and in some cases a prefix. Generally the basic number is adequate for engine identification, if additional information is needed the prefix or suffix is included. The change level number is advanced only when a replacing part or assembly being introduced and the old part or assembly it replaces are not completely interchangeable.

These Engine Code Numbers and their designations are shown in the following chart:
 

Also see:

1973-1979 Ford Truck Engine Identification Tag Codes (at FORDification.net)
     A complete listing of all engine ID tag codes for '73-'79 F100/500 trucks

1973-1979 Lincoln/Mercury Car Engine Identification Tag Codes (at FORDification.net)
     A complete listing of all engine ID tag codes for '73-'79 Lincoln and Mercury cars

1973-1979 Ford Car Engine Identification Tag Codes (at FORDification.net)
     A complete listing of all engine ID tag codes for '73-'79 Ford cars