WAI DST3890 Distributor (And Other Chinese Variants)

I had a 383 that had a orange wired pickup and I had a hard time setting the timing, the mark was all over the place. It ran o.k. but not great and I checked the gap and it was good and everything else checked good he just did a tune up so everything was new.
I noticed the wire and looked at all the small block dist I had, all where orange, all the big block ones where gray and I had a dist for a 383 so I just swapped them.
Timing mark was rock solid and the guy said it never ran this good ever sense he has had it. I called my buddy that has a starter, alt, carb, dist, repair business and he told me he has both and if you mix them up it will run but not the way it should and you will have problems timing it. Exact problems I had. He told me the GM's are the same way.
I also noticed the reluctor, on the Chrysler dist they go in different places for BB and SB.