Alps 622M -10k super soft feel fader

I have a couple of these removed from scrap Soundcraft boards though they were

I have had a new lot of these arrive and it seems there are some factory variations

I have 2 with a black top like in the first photo they are marked 303M-10K I thought the 303m was just a lot number but maybe not.

I have some new ones in they are wired differently marked 924M-10KA and have a silver top