Originally posted by techinspector1
It could be anything including a 390. Ford put 427's in those cars in '64 and called them a Thunderbolt. It's much more likely that it's a 221, 260 or 289, but like I said it could be anything.
Well, actually the Thunderbolt wasn't made by Ford but by an outside firm for Ford and sold through Ford. Only roughly 50 or so were made and they required special shock towers, upper control arms, tied subframes, nine inch rear and a lot of work.