I've always considered 'vintage' tractors to be anything from before things were standardized. Things like the 3 point hitch, live PTOs, integrated hydraulics, and loaders with two evenly spaced plate steel arms with tilt/curl/power down. The 'variety' days if you will, when everybody was trying to work around everybody else's patents and you ended up with every manufacturer coming up with their own unique system that only worked with *their* implements (things like Case's Eagle hitch, for instance). And then anything from that era forward to roughly 30 years ago is merely 'antique'
The way I see it as well.
Sometime between the very late 1950's to the late 1960's most tractor makers integrated the "modern" standard basics.
Available power or assisted steering (need that for the FEL),
ability to get a normal looking FEL mounted up,
decent volume and pressure on the hydraulics ( 2 or 3 pumps),
2 stage clutch, or even a fully independent PTO, a 540 and maybe a 1000 RPM
transmissions manual with live clutch or powershift, no longer stuck with a groundspeed transmission locked to the PTO so no over running clutch needed,
gearing with enough spread in speed to run a tiller to roading the tractor,
decent standardized 3 point lift of at least 1500lb,
Lockable rear axle.
Lights.
This ignores the need to have MFWD, that took a while longer to be considered almost a necessity.