Excluding, Walkers, Pattersons and Dragoons I'd say 3.
The '51 Navy frame was used for the '60 Army (water table modified) and '61 Navy
The Baby Dragoon used the original short pocket frame (1-5/8") but the later Pockets used a slightly longer frame (1-3/4"). The Pocket Navy and Police also used this frame but their water tables were also modified for .36 caliber.