I know dave, this is the 1980-1985 version GE M-250R......the 1970-1985 is what we call the GE M-250R1....I know this one is after 1980 due to the drip holes.....but the internals look different from my 1980 GE M-250R1
I didn't see many FCOs in MD until roughly 1995......I know a small group of GE M-400A1 FCOs in MD...which I remember seeing way as far back as 1986....but haven't confermed what reflector it has....I always saw it from eye level while traveling past it on a raised road and the fixture was on the lower level...
As far as I know, they aren't interchangeble.....the latch is slightly different and the front part the rim is smaller.....meaning there's no pointy front, I believe the front area space was elminated on the newer R2
What is the voltage of this ballast? The insides of this look VERY similar to the insides of my M-250 R1 FCO. It also looks like this fixture has a reactor one-coil ballast, like in mine. Mine is wired for 240 volts, and can only be used for 240 volts as there are no single-coil 250w HPS reactor ballasts for 120 volts.