i have a 64 elky but when i go to find parts i usually can't find anything for a 64. but i can find stuff for a 65 and i usually get that and it usually works fine. i'm just wondering if a 64 and a 65 are pretty much the same or if i'm just getting lucky.

No your not just getting lucky. Each generation (5) has numerous parts that will interchange within it's generation. Some changes within it's generation are just minor changes, some are extensive, such as a complete frontend re-styling. You could also use some, not all, parts from a 66 or 67 because they are within the same generation as yours.