From what I've seen, the earliest ones had Rotomatics, then Schaller M6, then back to Rotomatics before the final switch to Gotoh Sta-Tite type tuners. There may have been some diecast Gotohs used before the 2nd use of Rotomatics, but I can't confirm. But with Guild, anything goes. My '77 D-55 should have M6 tuners, but was factory-fitted with Rotomatics. Go figure.