I don't know. It'd be cool! The M-150 was the milestone for GE The first to have the plug-in igniter, the updated bail latch, the new street-side reflector for drop lens (the FCO M-250R1 had a similar reflector to the FCO A2s and R2s starting in the early 80s but before that used the drop lens reflector).
Also, it was the first light to use the tool-free photocell socket IIRC. Then in 1985 the M-250R2 rolled out. (that's why the two have different housings, since one came out after the other. the same reason for the M-250A being drastically different from the M-250R and M-250R1). The M-400A came out before the M-400 split door yet they use basically the same parts though... the socket bracket is different though (the M-250A and M-400A have the same socket mount and the M-400 split door and M-250R1 have the same socket bracket).
Then the M-400A2 and M-400R2 rolled out either with the M-250R2 or shortly after. The M-400A2 and M-400R2 have identical top housings. The reflectors are identical too. Only the bottom section is different. I think the reason the bottom sections are different is because GE wanted to keep the power doors the same (yet they chanegd the plugs so you wouldn't be able to use a new door on it anyways unless you cut off the plug and used the old one if you wanted to use an M-400A2 power door on a M-400A...)
I wouldn't mind an M-400R2 now that i have an M-400A2 lol.