The last 8 letters/numbers should match the VIN of the car it was originally mated to.
Federal law mandated that the engine be stamped with the VIN derivative.
jiho was correct in that is is an 85 Oldsmobile from Lansing with the last 6 of the VIN as 402265.
It matters not when or where the engine was produced. Those numbers/letters are stamped on the ID pad of the engine when the order sheet dictates a 3.8L is to be installed in whatever car the paperwork says and the "official" marriage of the VIN and that particular engine or transmission is picked. There's a tickler system somewhere that designates when the VIN is assigned to an order, and then everything about that car revolves around that VIN. The production office took care of all that and then parts were assigned for that model, etc., etc. Anything that needs stamping with a vin (frame, engine, etc.) gets stamped once that part gets pulled/assigned to that VIN order. The production office goes right down the line on the next sequential number when assigning VIN's. First come, first serve. You COULD NOT pick your VIN number. Maybe if you had $$$ you could. Ask me how I know. I was trying to get one with a "442" in it somewhere. I just thought it would be neat.
I can't speak for all cars and assembly plants, but I watched several 82 Corvettes get built when my dad still worked for GM. The VIN plates were stamped somewhere else, and they installed them on the "birdcage" (metal surround where the people go) with a power rivet gun. Nothing special. Pop- Pop! Done. Someone from QA would check the numbers against a sheet before it was installed and someone else checked the plate against the build sheet after it was installed.
Never in my life have I ever seen the VIN not match on an engine to the car it was born in. Could it happen? Sure it could. But remember in '77 or so when that Olds got that Chevy engine that started the whole "corporate" engine thing? Nobody wanted another Federal case. And if the factory mismatched VINs, then it very well could be a Federal case.
As far as parts made, then used later, much later sometimes, it's just a fact of life. For instance, Hutch (aka
oldsofb) gave me his old, original brake combination valve from his 87 442. Date code says it was built in July 85. Sometimes they used "Just In Time" production so the part build date would be a week or two prior to the car's build date, but that wasn't a big thing in the 80s. They didn't start building 69
H/O's until the end of March 69, but there's many
H/O only distributors with January 69 build codes on them.