The AD's were pickups known as Advance Design from 47-54.
Art Deco's which is from somewhere around 40 to 46...not sure about those years maybe it was 42-46? and referred to as Art Deco even though the initials also spell AD.
The inline 6 cylinder was known, or so its said, that the bolts holding the side covers on looked like stovebolts and the name stuck.....Now days Stovebolt generally means anything Chevy whether its a 6 or 8 in todays world.
Check out the tech FAQ and links ect and there is actually an article here on the site that describes it all for you.
http://www.stovebolt.com/faq/#stovebolt
