The Jeep crowd around here love to modify our Ford T-18s for their Jeeps. They also like the Ford 9" rear ends.
I asked why, and was told "because they are bulletproof".
So this could be the explanation why it has signs of both.
Truck: 1981 F-150 Explorer / Engine: 300-6 California MCU Feedback System / Trans: T-18 - 4 speed / 2.75 Ford Rear Axle Open Diff.