I have a '64 and put the '65-67 mounts and towers in it years ago. The reason they changed the mounts is because the '64 mounts don't have enough rubber area to them and they break. The '65 mounts are alot stronger and I highly recommend switching to them. Haven't ever had and of the '65 style break, but the '64 ones sure did break! My car is a 4-speed and when it broke, the engine torqued way over and the gear shift moved over about 3" when I got on the throttle!