Unless it was sold as a cab and chassis only, without engine or transmission.
The County road dept. here would buy medium and heavy duty Cab and Chassis, and have them outfitted with what they wanted. Usually the lowest bidder won etc... And that usually means Hodge Podge.
Truck: 1981 F-150 Explorer / Engine: 300-6 California MCU Feedback System / Trans: T-18 - 4 speed / 2.75 Ford Rear Axle Open Diff.