Could it be that 1 ton and down got "serial numbers" and 1-1/2 ton and up got "chassis numbers" because they were sold as Cab & Chassis and not complete trucks???
Mike B
Mike Boteler
1956 Chevy 3100 Resto Rod 1952 Willys M38 Army Jeep 1983 Jeep CJ7 Laredo 1984 Jeep CJ7 +++++ Silver Spring, MD