[Rev]

69Pony, if it came out of a '66 and doesn't have a later valve body the three forward gearshift positions are L, D(big dot), and D(little dot). From what you're saying the 2 position in your car is really D(big dot)in the '66. Does your car start out in 2nd when you start out in D? If it does then you have the regular '66 valve body, Select Shift Cruise-o-matic. That's the only reason I can think of that your car automatically shifts into third when you have it in 2.

Rev