Looks like it's mostly all there and ready to go to work. Can't see an air hose coupling coming off the air tank/air drier, but no big deal - it's only $3 part.
One thing noticeably absent in your pic is the horizontal O2 bottle rack (would be located directly over Gen head) but not all M1031's had them. Apparently EOD just wanted the trucks for the generator capability - No need for a torch, so no need for a cylinder rack, hence the bottle rack wasn't installed.
1031's come in two basic flavors:
Earlier 1031's used a gas engine powered welder (which did take up the whole front of the box). Supposedly the early SECM bodies were either leftover inventory or take-off bodies from the old M887 Dodges.
Later 1031's used a PTO driven gen head that *sometimes* (depending on what kind of unit it was issued to) also powered a Miller 3 phase arc welder. To the casual observer, the rear body looks the same, but the doors are slightly different from the earlier SECM bodies.
I have the later type, like the one you have pictured. The ID tag on my body says it was inspected (read as "accepted by Uncle Sam and installed on the chassis") in '89, but the VIN indicates the chassis was built by GM in '86. God only knows what the truck was doing for the time in-between. I don't know whether it was driving around with an old 887 body and it was later swapped during Depot Maintenance, or the Army just decided to a keep a "new" '86 cab and chassis truck waiting around for a bed for three years.
