Mark, looking at the list of trucks on your signature, I must be missing why you're asking the question, but just in case... Your original question was "is that the correct size for my truck?" I would suspect the answer as one of the other posters inferred is on the GM Heritage site in the online Vehicle Information Kits (original specification manuals). Here is the link. Make sure you scroll down the page to see the online document links.
http://www.gmheritagecenter.com/gm-heritage-archive/vehicle-information-kits.html
See if this helps.

1946 3/4 ton