The Stovebolt Site Forums The Shop Area General Truck Talk Door Lock

Probably have to buy used, no one was selling them when I needed one years back.

http://chevy.oldcarmanualproject.com/parts/1929_54/758.htm

http://chevy.oldcarmanualproject.com/parts/1929_54/762.htm ( group 16.365 )

As you can see in the first link, there are a lot of part to the lock assembly, the second link shows that all trucks up to '42 use the same cylinder.