that's the engine number, which is mostly what was used back then to register a vehicle .... if it doesn't still have that original engine installed you have some work to do with titling to prove the title really belongs to the truck

Bill


Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot