I have no idea, I never worked with a Powr Door GE fixture until I got this one. the ballast doors I've seen on Ebay for HPS have the white connectors your talking about.
Typically they all had the white connectors (even MH and MV). The M-400A2 replacement powr/modules came with an adapter plug that converted the white plug to the black plug so you could use a M-400A2 door to fix a burnt out M-400A ballast door. Otherwise you'd just discard the adapter plug to use with an M-400A2. I had assumed the newer M-400As were the same way. The M-250A2s were. Kinda cool to see the old plug used.
Probably not. Kinda strange. Here's an example of what I was talking about. Note the black plug's other end plugs into the ignitor base. Any 1985-present GE Powr/Doors I've seen use that white plug. The adapters were just to allow existing M-400As to be kept in service, otherwise the installer was to remove the adapter and plug the fixture's wiring harness right into the ignitor base.
The physical M-250A2 doors themselves were all interchangeable but the very first M-250A2s (M-150s) used the black plugs. I'd imagine they offered the adapter plugs for those as well. But mechanically, all the M-250A2 ballast doors are interchangeable. By the mid-80s they were using the white plugs so any post-1985 M-250A2 door I'd say is interchangeable with any other post-1985 M-250A2 door. The M-400A and M-400A2 ballast doors are all interchangeable too (mechanically that is; you need the adapter plug to make them electrically interchangeable).
From what I understand, GE offered replacement M-250A ballast doors until sometime in the 90s (remember those 150W ones you posted a long time ago with the chubby "15" font? I think those were late 80s or early 90s ballast doors). All of those would have had the black plugs since they never made the M-250As with the plug in ignitors or the white plugs.
GE was pretty good about keeping replacement parts available for their fixtures. I was told M-1000 parts were still made into the 1990s as well as M-250R1 parts. And they kept things such as the tool-free PC socket compatible with older models (non-tool-free PC socket; they're compatible). And same with the M-400A2 doors vs. M-400A doors.
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From what I understand, GE offered replacement M-250A ballast doors until sometime in the 90s (remember those 150W ones you posted a long time ago with the chubby "15" font? I think those were late 80s or early 90s ballast doors). All of those would have had the black plugs since they never made the M-250As with the plug in ignitors or the white plugs.
GE was pretty good about keeping replacement parts available for their fixtures. I was told M-1000 parts were still made into the 1990s as well as M-250R1 parts. And they kept things such as the tool-free PC socket compatible with older models (non-tool-free PC socket; they're compatible). And same with the M-400A2 doors vs. M-400A doors.