Engine block ID

Mid to late 70's exhaust manifolds. Look on the block next to the starter and post what's cast there. The casting number will be similar to what you posted for the manifolds. The date code will be a number/letter/number combination. That combined with the casting number will tell you when it was built but not what vehicle it was originally installed in. You'll never know that by just the casting numbers, you'd have to track down the history of that particular engine and who did what with it, to find that out.

I don't have a book with 351W casting numbers that new but it's an 1990 model year block, cast on September 14, 1989 More than likely came out of a pickup or full size van. Some were put into full size Ford's,Merc's,& Lincolns, but the majority were put into trucks and vans. Sounds like someone did a bit of junkyard swapping to put it into the 69 Stang. Look at the heads and see if there's a large "S" or "T" cast into one corner, next to the valve cover. "S" heads are E6SE's, high swirl/torque heads. "T"'s are the better ( by 25 horses on the top end) Stang/Pickup/Van E7TE heads. No letter there? Then look inside the valve cover and see what the date code is there, and/or look under the intake runners and get the casting numbers there to see what heads they are.

The "T" I was talking about is at one corner of the head next to the valve cover, but outside the cover.