I've had all of these cabs at one point. The order in which they were produced is as follows:
1 - Gray VS cab: Made in Japan, meant to be a dedicated VS. It generally has an EZ in it, but it may have also have a Sharp.
2 - Black VS cab: Made in Japan, originally was gray but was re-painted black at the factory to be re-skinned. This was used for R-Type and in rare cases, dedicated PC-10 single monitors. I say rare cases, because there are a lot of conversion kits out there that were used on the gray cab or r-type cab. Some collectors have said they have a dedicated PC-10 in this type of cab, although I have never seen one with the "Dedicated single monitor PC10 made in Japan" serial tag. If they are out there, I imagine Nintendo started using the last of the leftover R-Types to make dedicated PC-10s before switching to the cheaper version (see #3 below)
3 - Black dedicated PC10 cab: Made in the USA with a K7000 and a weird sound amp. It was particle board and more flimsy than the original cab. It also has a slightly different speaker grill on top and as you have all called out, it has the single hole for double coin doors (to save money I imagine).