Interesting S'G' Trigger Housing on Ebay

[USGI]

I see what you mean about that notch looking different, but I think part of it has to do with the camera angle. The WarBaby III reference listed by JimF shows that later production S'G' housings have incomplete or no locator holes at the rear. Also mentioned is that early S'G' triggers have a "notch" at the rear. I thought I had two of the S'G' housings, but just found one. I'm attaching the pics. The barrel date on the carbine that goes with it is 8-43. You could always buy it and figure out later if it's worth anything - that's the way I usually do it! - Bob