6X have the 1.66 exhaust valve, whereas the 96 have 1.77. Make a difference? Probably not one to be felt underfoot.
I've met a few very stout 455 with 7K3, they're a bit of a sleeper head. Of course, it doesn't take much to be better than the 7M3s the 72 455s had on them!
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching
