If it's a '51 Chevrolet, it would be a 2 ton. Need a few more specifics. Get the number from the ID plate in the driver door jamb. That number will tell if it's a 1 1/2 ton, 2 ton etc. Weight of a '51 Chevy 2 ton would be between 4500- 5000 lbs., in cab, & chassis form.