340 exhaust manifolds
You probably have seen 2 different styles of manifolds since there are two. Check out TTI's site as they make exhaust pipes for all the various styles.
http://www.ttiexhaust.com/MoparClassics-Exhaust/MfdCastingNos-340.pdf
You'll notice there are photos of the styles and part numbers; take those part numbers and google them to get larger pictures so you know which style you want to buy.