i have a 65 with a 302. how hard would it be to install a rear sway bar if it didnt have one already? and what size sway bar do you recommend?

 

Be sure you know why you need a rear sway bar in the first place. Adding a rear sway bar not only reduces understeer, it also makes the car more likely to oversteer. -- for the rear end to lose adhesion and swing out when cornering. That makes the car more fun to drive (it turns quicker), but also more dangerous because it could lead to a spin-out. To correct for oversteer, the driver must stay off the brakes, add power, and turn the steering wheel in the direction of the slide -- a design considered indefensible in court, and one that could expose Ford to liability. So, don't go crying to Ford if you spin out and damage something because you don't know how to drive with a rear anti-sway bar.
On size, the front anti-sway bar must be larger than the rear. So, let's say you get radical and get a 1" anti-sway bar for the front, then consider something in the range of 3/4 inch for the rear.

 

Nicely said Glen - all of it. As Glen mentioned, you should upgrade the front sway bar before adding a rear. Your classic will most likely have a teency-weency front sway bar, and adding a 1" bar to the front would do more for you in cornering than adding anything to the rear.

As for difficulty, I've seen two styles of rear sway bars - one is a pain to install if the car is not on a lift, while the the other is not that bad. I had a pro install my 3/4" rear bar at the same time he was welding in my sub-frame connectors, so I spared my knuckles on that one. If you're just starting out on the car though, your money is better spent elsewhere on SEVERAL other mods...

Good luck!