One of the first trades I made over 20 years ago with my "brother from a different mother," Dale53 was for one of those early slide-type Number 55s he had owned for many years. I found it a bit less handy to adjust, but wanted it to fill a spot in my collection between the late #5 and the more commonly seen micro adjust #55. Just to show it could be done I also installed a later #55 rotor into an old #5 body I had laying around. The outer diameter of the rotors has been unchanged from the nineteen teens to the newest ones I've checked.
Froggie