More than likely your truck was originally titled back in 1952 using the engine serial number KBMxxxxx. The engine died and was swapped out, so someone had a new tag made with the original engine number and stuck it on the truck so it matched the title.
Once either the engine or chassis serial numbers were used for the title, the other number became legally useless...there was never a record of which chassis got which engine.
Chevrolet stopped stamping engines with serial numbers after 1956, so from then on the chassis number had to be used for titling purposes...it wasn't an option.
Mike B
