65 Comets have a lot of the same parts as mustangs, as with most 65 Fords. The doors will swap with the 64. Sheet metal is unique to that year. Check Auto Krafters for most parts. Most parts are not as plentiful as mustang, but are not usually that expensive, as this is the off year for collecting. 64 & 66 are more desirable, so you shouldn't get in too deep, if you pick your parts sources carefully.