Speedometer Cable Adapter GM Cable to Ford Slip-in gear drive
Transmission speedometer adapter to convert from a Ford Slip in driven gear drive to a GM speedometer cable.
Used a lot with Ford T-5, all 3550/TKOs, Ford T-56 with cable drive and all Tremec Magnum six speeds.
For Driven speedometer gears and retaining clip see here. Ford Driven speedometer gears