What is the serial number on your cab? What makes you call it a 1-ton? A '53 GMC 1-ton is a 250. Not every GMC with duals is a 1-ton.
If its a '53 GMC serial number the first three numbers will be the model number and wheelbase. I would expect 253 if your truck is a 1-ton. In most cases there will be no letters in front of those numbers. If there is one letter it has special meaning. If there are two the truck probably is not a '53.
I would expect your serial number to look like 25324 followed by a letter indicating which plant it was built at if it is a 1-ton.
If those first two numbers are not 25 the truck is not a 1-ton.
