Welcome to the Stovebolt community M77 Longhorns!
Thanks for providing a great batch of 1st pictures to help us help you figure out what you have.
Since you indicated a 1948 starting point, check out this 1948 Chevrolet Truck Data
] file provided through the Gm Heritage Center web site.
A quick check of this document shows the engine serial number you provide in your picture (FEA 95648) to be a 1948 "235" that would have been installed in a 6000 Series (2 Ton) truck built at the Flint manufacturing plant.
The engine casting code in your picture "3693374" along with the "circled M" and 48 confirm its vintage.
To further confirm the truck to be a 2 Ton, you can take and compare measurements of the truck with those in the above file to confirm which model you may have.
Hope you find this helpful and looking forward to more questions as you have them.