Steven, the '66 box states a 425 engine, but you can change the induction system and air cleaner decal with parts box extras or aftermarket pieces to represent any of the available engines, since externally they appear the same, being based on the same block casting. The chassis is nicely done, but should be 2 scale inches too long for a '63, as I think they rode on a 117" wheelbase, whereas '66-'70 were on a 119" wheelbase. Easy enough modification, especially on a X-frame; just take it out of the center area, and shorten floor pan to match. If you want to see what's in the box, here's a nice video peek: