Thanks BarnieTrk!

I checked the vin plate and yes, the number is 381 for the body - perhaps a typo on the plate itself??? The original owner told me tonight that he bought the truck in northern New Mexico in October of 1965 so your decode seems to be accurate. As for the wheels, the manual says they are 16.5 but the actual tires show 16 and they are bias ply (snow tires in Phoenix!) and the wheels have the "innie" tabs. My desire to swap out the rear end gears is because the 410s make the truck wind out at 55. If it had a v-8 it would be fun, but with the 240 it makes the truck less useful in Phoenix where there are so many highways. It looks to me from checking out the differential cover that it is a Dana 60 rear end (although a mechanic said he had never seen a Dana 60 in a 1/2 ton stock with 5 lug wheels). The original owner told me he ordered the truck heavy duty for working bees - and that nothing was ever changed in the truck - I have service records, warranty card, manual, extra parts, etc and everything is original How can I tell if the differential is a Dana 40 or a Dana 60??? Sorry for the long post - I am new here and there issues are probably dealt with in other posts.

Civicminded.....