This is the GE M-1000. This is the 1000w version of GE's M-series of cobraheads. This looks like an early one. There's no bolts on top and this has the older version of the door. this may actually have a ballast inside it. The ballast can may have been for the previous light.....

@streetlight98, thank you again It must be one tight squeeze to fit that 1000w ballast in there!

No Michael, this is not the earliest one, but it is a late 60s-70s version, the earliest one was silver colored one with a FIN on top for room for capacitors! They changed the GE M-250R and GE M-400 in 1970 in the fixture designs but kept the GE M-1000 design longer...until closer to the 80s, not sure exactly what day. Note it has a thumb latch...

I said it looks like an early one.i know it's not the earliest. All the origional GE cobraheads were silver like you said.

I think the M1000 got a redesign sometimes in the mid-late 70s before being discontinued in 1983. But I've heard separate parts are still being made.

I don't know about that. i contacted GE about a year ago when I got the 1977 catalog and they said the M-1000 parts were discontinued in 2008.

Amazing that they made Replacement Parts for a model that had been Discontinued Years Prior.

i thought the M1000 was discontinued in 1987?

Something like that... The catalog I got in '77 still showed the older door.