Largecar04,
I did some further digging in the GM Heritage site and based on what I found
1946 Chevrolet Truck "brake" data, your parking brake setup consisted of the transmission mounted hand brake lever assembly that actuated the rear axle mounted drum brake shoes through a rod and cable system. See the below screen shots taken from the page indicated.
I thought you may have been describing a "transmission mounted" drive line parking brake setup like is found on later AD series trucks. My apologies for getting this wrong. Turns out there was a "drive line" mounted parking brake setup, but was only an RPO for "buses" so doesn't apply to your 2 Ton.
For further diagrams and part number info, you should look through this
1941 Shop Manual which I think remained the same through 1946 due to no model changes during WWII. You may also want to look at
Chevy Master Parts List 1929-54 which lists parts and some diagrams that relate to your '46 parking brake needs.
Hope this info is helpful.
Dan