I installed one of the 65-66 tanks in my 68 Catalina. The primary differences are the filler neck and the strap placement. the strap recesses are farther apart than the 68's, but fortunately the two narrower recesses just inboard of those line up perfectly and the straps will just fit. I was also able to swap out filler necks, but would recommend you let a professional do that part as my solder job was not gasoline tight at first. You will have to get the accompanying sending unit too, since the hole is too small for the 68 unit. Lastly, I had to tweak the lock ring receiver(for lack of a better term) to get a tighter squeeze on the o-ring because I also had a leak there on my initial fill-up.
Good luck with it!
Ron.
__________________
|