more likely that number is the engine number, commonly used as the title vin back then, check for an engine number - if the engine has been changed the title should have been changed at the same time, although most folks didn't bother to do that
"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