What Vehical Is This From?

HELLO, I DO ALOT OF METAL RECYCLING. I FOUND TWO CYLINDER HEADS THATAPPEAR TO BE FROM A V-8 ENGINE. IT IS MARKED T581665, THE EXHAUST MANIFOLD IS 381921 ALSO HAS A D4?:banghead: HAVING A HARD TIME TRYING TO FIGURE THIS OUT. PLEASE HELP.

I'm moving this to the Engineering/Technical forum as I think you might get some better answers there.

Could they be from a mid-60s Oldsmobile? A search on Google for 381921 manifold leads to a couple of sites which identify the manifold as such. The classicoldsmobile.com server appears to be down at the moment but you can click on Cached to read the Google caches of the pages: Link (http://www.google.co.uk/search?hl=en&q=381921+manifold&btnG=Google+Search&meta=)

^^ I agree.
later '60's to '70's Oldsmobiles did mark their heads with the letter C,D,E, etc on the lower left corner, (when installed)as I recall.