Looks like your truck could be from 1 ton up to 2 ton. They were all available with 137 inch wheelbase.
The first few pages of
THIS have some information on vehicle serial number configuration. It consists of model and year code, assembly plant, and serial number. If your title has the correct serial number configuration you should be good. It may have been registered by engine number.
Be sure to check with your DMV on building a replacement data plate. It could be illegal in some states.
