I am not as familiar with the pre '47 trucks as the AD ones, but there are a few pictures that I found helpful.

Possibly the best for your application, a picture of some Huck style brakes:

http://s1291.photobucket.com/user/R...0Boards/IMG_79851sm_zpsfa49071e.jpg.html

From the 1954-55.1: (Bendix brakes)

http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0514.html

A little more modern style:

http://67-72chevytrucks.com/vboard/attachment.php?attachmentid=443547&stc=1&d=1237682954

I think (and am not certain, someone else on here may correct me) that your truck has Huck brakes on it. The parts are hard to find. I have a hard time finding parts for my 1955.1 chevy 3600; I can't imagine trying to find older parts for the Huck systems. You may have to fab some parts if you can get schematics with dimensions.

For more discussion on parking brake systems, there is a recent thread:

https://www.stovebolt.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=1085556#Post1085556

Good luck!