The "Machine Head" Strat from Dec 1971.
The "Machine Head" record from Dec 1971 was a milestone in Deep Purple´s history. So the main guitar which was used by Ritchie during this recording session, becomes legendary. For the session, two Strats were at the ready - the rather new early 1971s sunburst one-piece maple neck with skunk stripe and unlacquered fretboard and the older black maple neck as a backup. The 1971s sunburst had an unintentional special feature by the Fender factory. The facts: this 71s guitar neck was yet fitted with a 4-bold neck screw but with a skunk stripe. But at the headstock, it was not fitted with a bullet like a regular 71s Fender Strat. Above the nut was a walnut spot, furthermore only one string tree was installed instead of two and with the "WITH SYNCHRONIZED TREMOLO" logo. This neck was obviously a mix from the specs of a 70s Strat neck with some details from the new 71s Strat necks. Or in other words, this 71s neck should have a bullet and a 3-bold tilt-neck attachment. Remember, exact during this time (early 1971), Fender switched the neck design from 4-bold to the 3-bold adjustable neck and a few other features regarding the neck. I assume that there are several existing transition-solutions, to use the existing stock of already produced necks.
Ritchie used this "Machine Head" Strat as his main guitar between early 1971 and early 1973. This axe was used at the Beatclub show (Sept 71) and the Machine Head recording session (Dec 71) until summer or autumn 1972. Then during a heavy showcase, this fine guitar was rather damaged by Ritchie at the headstock. Nevertheless, Ritchie played this guitar until early 1973. Than the axe was finally destroyed by Ritchie and was replaced by a newer 1972s sunburst Strat with a scalloped, lacquered fretboard. This guitar carries all specs of a standard 72s Fender Strat like a bullet truss-rod at the nut and 3-bold tilt-neck.
My special credit to Eddie from www.eddievegas.com, an extra-fine Fender special shop, for his friendly permission about the pics about this ultra-rare Strat neck. Here, Eddie's full picture gallery about this neck.