The AD trucks came from the factory with the springs unpainted, as were the transmission, front axle assembly, rear axles assembly drive shafts and steering gear.
If you go to the original size on this picture you can still see the green id paint that was on the bare front axle on most of the light duty AD trucks.
http://www.pbase.com/dennygraham/image/113628961/large The bottom of the cab was bare also except for paint over spray at the edges and a strip of under coating on either side. The chassis was painted black before it went to assembly.
GM was in the business of building and selling new trucks and these trucks were not made to give several decades of service. They were built to last about eight or ten years at the most and be replaced. As noted in some of the old parts literature which I remember from when I was a Chevy parts man, they did no promise that new replacement parts were to be made available after ten years and many parts that were not common to later years disappeared from the later parts books after a decade.
The majority of the restorations that I see (as I also do) paint all of the under chassis parts semi-gloss chassis black, which is technically incorrect but generally accepted by judges. In some cases such as the transmission, center section, master cylinder, steering gear I use the Cast Coat simulated cast iron paint from Eastwood.
Denny Graham
Sandwich, IL
