Hi There first time user here. I purchase some 1973 strat pickups and when I had them rewound I found the pole spacing was 50mm, smaller bobbin more turns to get the same resistance. So I am wondering if Fender had some criteria through the "Vintage years" doing this. The pickups are stamped correctly and look authentic.

Pole piece spacing don't change when pickups is rewound.

Late 60s & 1970s pickups, from The Fender Stratocaster by A.R. Duchossoir

wire is #42 GA
number of turn 7,600
Magnets alnico 5
resistance 5,700 ohms
inductance 2.2 henry
Q factor 2.4
Top frequency 6400 HZ

I hope this help you