This grease cap protect the end of the spindle.
1964 ½ -1966 MUSTANG 260 & 289 V8 Engine
1967 - 1969 MUSTANG EXCL BOSS 302, BOSS 429 AND 69-70 SHELBY FROM 4/69
1970 - 1973 MUSTANG EXCL 70 SHELBY FROM 4/69
1979 - 1993 MUSTANG FRONT
1967 - 1973 COUGAR
1963 - 1965 FALCON 8 CYL.
1966 - 1970 FALCON (BEFORE 1/1/70)
1955 - 1957 THUNDERBIRD
1957 - 1968 F100 4X2
1957 - 1967 F250 4X2
1970 FALCON (FROM 1/1/70)
1968 - 1970 TORINO
1964 - 1970 FAIRLANE