Thinking of buying a 1970's Vintage Strat? Its a lot of money to shell out for a Strat before you have checked it out (or even seen in the flesh!), so here is a quick guide for you to check various parts on the guitar. Any seller worth his / her weight will answer these questions no problem, or provide pictures where necessary.
I'm not going to treat you like an idiot and suggest things like "check the pegheads for the right shape and logo"...everyone knows that Strats were only made in the USA throughout the 70's, so ALL Strats had the big heads with the curvy "Stratocaster" logo....but check the word "Fender". It should be a deep black with a silver outline. Also check the condition, it should be a little worn in places and maybe a bit of rust on the metal? But these are obvious ones huh?!
Anyway.... onto the guide.
1) check the tuner covers. Fender used Kluson tuners up until the late 60's. Afterwhich, they had tuners made for them specifically with a big "F" written on the covers. In the 80's this changed again, so this is very poignant for late 60's to late 70's Strats.
2) The Neckplate (the piece of metal just behind the base of the neck, on the back of the body), should be a rounded triangular shape, with 3 bolts and a big "F" in the centre (this was a feature from 1971 to 1980). The serial number was present here until about 1976, if the serial number is there is should begin with one of these:
280000 to 300000 = 1970
300000 to 330000 = 1971
330000 to 370000 = 1972
370000 to 520000 = 1973
500000 to 580000 = 1974
580000 to 690000 = 1975
690000 to 750000 = 1976
After 1976, the serial number transfered to the peghead and will follow these patterns:
S6 + 5 digits = 1976
S7 + 5 digits = 1977-1978
S8 + 5 digits = 1977-1978
S9 + 5 digits = 1978-1981
E0 + 5 digits = 1979-1981
3) Check the stratchplate.... in the 1970's models the top side (as you play the guitar) had 4 screws, the one nearest the centre pick-up is the most important to check. this should be almost directly above the pickup... its slightly to the left (for right handers) but no more than 1cm. in the later models, this screw was moved to be more central between the middle and neck pick-ups (almost EXACTLY in the middle of the 2).
These 3 checks CAN be faked, but its unlikely anyone will be THAT good... so if all three are present and correct, could be worth having a closer look for the more intricate details.