I herded a couple of "Goats", both new. Foolishly, I traded the '65 in on a '66.
I really loved the lines of the '65, giving the '64, the original year, a close second in good looks over the entire GTO run. The problem with the '64's? Pontiac neglected to beef up a Tempest frame, so they had trouble handling the torque of a 389. Like the Beach Boys song lyric: "I get pushed out of shape, and it's hard to steer...".
Braking power was horrible...a big engine dumped in a car designed for slower speeds...miserable little 13" drum brakes that would fade a nanosecond after you applied them at triple digit speeds.
My '66 Goat? Even new it was poorly put together. I'd ordered this car, and I was disappointed in fit and finish, to say the least. I drove it 4,000 miles or so, then bought my first Porsche, a '66 912. Haven't bought GM since.
Tri power left the GM scene in the middle of the '66 model year. '67 brought disc brakes up front, and they were sorely needed. '67 also brought the 400 cubes engine.
My memory fades after this...
Tabby? Nice "stang"...I'm sure it was very fast (in a straight line) for it's day. However, here I go with "lines" again. IMO, the Mustang got pretty fat after the '66 model year. Aesthetics NOT pleasing to me.. Sorry, but don't think I'll be beating your door down with an 85K check in hand...

So, if you find a sucker, you'll replace the Stang with a Cayman???