Ford - F-450/F-550 Superduty Chassis Cab - Overload Helper Spring (Rear) gmc-k10-pickup-4wd-1973 which means you don't have

which means you don't have to worry about it suffering from the classic rotting and rusting away problem that so many Ford hangers and shackles have had

This bushing is used in several other leaf spring applications as well

1964 - 1969 Barracuda

This is a Standard Duty replacement for the stock three leaf spring

This is an OEM replacement steel encased rubber leaf spring bushing for leaf springs on Chevy and GMC

Ford - F-450/F-550 Superduty Chassis Cab - Overload Helper Spring (Rear) gmc-k10-pickup-4wd-1973 which means you don't haveOEM # F81Z5560BB F81A5560BD This is a direct replacement for the stock single leaf helper spring.