The "smaller switch" is used in the Euro Capris in 70-72ish. The Pantera one has always been mentioned as being a Capri switch....but now I am having my doubts. It is a 71 piece.... and I am going to guess that it came off of some larger sedan or truck.
I have an NOS GT5 switch too, but it has the main body at a 45ish degree angle instead of a hard 90 degree to the column. I have notes I took somewhere...outlining the different diameters....so should check and see what size the GT5 switch is! These tended to be 74-76ish Capri's....from what I have found in the wrecking yards. The rear switch portion is indeed interchangable, and some even have a couple of more wires on the back, but I believe that they are for the "key present" buzzer....
Larry-you sure I didn't buy those switches already????

Steve