the heads have wf for windsor foundry where they were made i guess cast in to the heads on top. i really think all windsors were made in windsor but what thats what mustang and fords said. they also said short of hipo heads they are the best factory heads to go to for early models that dont convert.
The 78 and later 351W heads are the same castings and valves as the 302's. The 69-74 heads are the small chambered bigger valve heads, the 75-77 heads also had the big valves as I understand, but larger chambers. Fostang--- if you're looking for a set of the early Windsor heads, I've got two sets to sell. Both are cleaned and mag'd, no cracks, never reworked. Both sets are the D0OE-C heads.