I've never really found anything that described which engines/years got the fixed pickups and which ones got the floating or swinging pumps or whatever you'd like to call it. There were a few different pan configurations available as well (center, rear), so it may have been linked more to that than the model/year. I have one somewhere, it was on a short deck DeSoto (276/291).
A 318 poly fuel pump is the same as a LA 318 fuel pump. They fit, but you really need a spacer to position the arm correctly. The pump arm on the early hemi's is shorter, so just bolting up the later fuel pump doesn't locate the cam on the arm in the right place. It will work, but it works better with the spacer. Hot Heads sells them on their page. I run a hi-volume Carter fuel pump on the 270 poly in our '55 Coronet, with a spacer.
