I have a 1965 Mustang. It is almost certainly the upper control arms. As far as parts for your car, they can be bought in lots of places. NationalPartsDepot.com is where I buy most of the things I need for my Mustang. There is also California Mustang, Johns Mustang, Virigina Mustang...lots of places. You can buy virtually any part you need for that car without going though a mechanic and paying a markup. The parts are new reproductions, mostly very good quality. If you want some help with your technical questions and want to hang out with a bunch of other classic Mustang owners, go to http://www.mustangforums.com/forum/classic-mustangs-16/
That is the Classics section of Mustang Forums. I am a member there and the members love to help other people out with advice. We would be glad to have you.
Right on the money LeonardA, you are absolutely correct
The most probable source of this squeak is from the upper control arm bushings which are of a metal on metal design on your Mustang.
Because of this setup, the bushings need to be lubricated faithfully, penetrating oil won't help at all.
Some so-called 'mechanics' used to burn holes with a torch in the inner fender to gain access to the grease fittings, a true sign of a butcher
Google upper control arm bushing lube kit and your good to go
first thing i would look at is the upper and lower control arm bushings.
i used to have a 1974 ford maverick that had squeaky bushings . i put a kit into it that would allow me to use a grease gun to grease them up so i wouldn't have to dismantle the arms.
fixed the squeaking.
any tips and help , i got a bud who operates ray greer's mustang
alley in hanford california.......559-584-2285.
he can get parts for any mustang prior to the mid 70s.