dual pickup distributor for a dodge 440 ?

The only electronic dual pick up ones that I have seen were from early 70's emissions era engines, and I think big block only, but I could be wrong. The second pickup had something to do with altering the timing for emission control. The housings to the best of my knowledge are similar between b, rb and a engines, but all three use a different shaft length, and remember that small blocks turn clockwise, and big block ccw, so you cannot interchange the internals or vacuum advance canisters between big block and small block.