The GMC CCKW

Were there troopseat chains on cargo CCKW as we can see on this picture?

I never saw any on the CCKW "Lazy Backs" (Troop Seats). Tha Drawing you posted is a Chevrolet Style Cargo body. The braces that fold under the seat are sufficient.
Joel

Probably typical Army over engineering. If one is good then three makes it better.

I don't think these chains were supposed to hold the seats. I think they were supposed to stop the poor soldier who would have slip on the bench and fall from the truck. There are same chains on Dodge WC trucks.

I'm would be happy that there were not on CCKW's beaucause I don't have them and I have enought missing things to look for

The duty of the Wheeled Vehicle Driver is to raise the Tailgate and secure the Safety Strap that goes across the rear of the Cargo Body. The Driver is responsible for the safety of the passengers.
Joel

The fun part of restoring these old critters is finding the missing parts, and espeically when they are found at a bargain.