I think you’re right. Has more the look of tooling than aircraft part, just to my eye. Don’t they stamp numbers on tools so they can track them down when someone forgets one inside a plane?
"Part Number's," were put on "Tooling-Fixture's," but were done more for inventory control, location purposes. Looked more like say a VIN-Tag, on a car firewall. Lot's of information was on those tag's.
FYI: Their was "Boeing Aircraft Inc," Boeing Holding Company Inc, (ALL TOOLING assigned to this,) Boeing Auto Sales Inc. (Yes, with the literally thousands of vehicle's {Car's, Semi-Truck's-Trailer's, Buses, etc., SPECIAL-USE-VEHICLE's, owned by Boeing,}) State of Washington Made them get a "CAR-Dealer's-License." They were audited ever year, so Washington State would get their "CUT" of the Vehicle Excise Tax.
Could you imagine when the State of Washington found out that maybe as much as a quarter (or more) of Boeing(s) vehicle's, never made it onto public roadway's, i.e. just used on the private property belonging to Boeing, not opened / used by the public. That must have left one hell of a mark, dollar wise, to the State of Washington. OUCH!!!
Me or you would think purchasing say 10 (ten) or 20 (twenty) Semi-Truck-Trailer's, would be a big deal. Boeing would purchase as much as 100 (one-hundred) Semi-Truck-Trailer's. Not all vehicles were from one manufacture, they would split the ticket so to speak, say 50 Freightliner's, 50 Peterbilts / or say Kenworths. Would ALWAYS, be Licensed / Registered under Boeing Holding Company, (Washington-State/ Delaware-State (Main legal location) Corporation,) without a doubt.
At the time Boeing was in California, Washington, Texas, Alabama, and Florida. (circa: 1986-1992.)
Back to the part, maybe Landing-Gear, or more likely, from a "Cargo-Aircraft-Layout," Load/Un-Loading part. Just my two cent's worth.