no parts houses in town has front calipers for my 72 charger so I thought i would rebuild them, any special tools that i need? also, how would you get the piston out?

air compressor and a brake hone to clean up the cylinder. just put compressed air into the hole for the brake line and it should pop out. Wrap it up in a rag or something it might come out with some force. The rag wrapped tight will contain the piston. If need be you could probably take the caliper off the rotor and leave the line hooked up.
Step on the brake peddle. Out pops the weasel. Would be quite messy that way tho.

I tried useing the brake pedal to pop the piston out but I think its rusted in. any other ideas?

If its that badly rusted in place, you are probably better off either sending it out someplace and let a pro handle it and have it sleeved due to the rust pitting or check out rockauto.com and see what they have in stock.

Be careful of the compressed air trick if there is any resistance the piston will build up pressure and when it does blow it will be loud and possibly ugly. DAMHIK

If you can not get the piston out easily with compressed air I suggest you use the hydraulic pressure from the brake pedal. If it still will not move it could be cocked in the bore. Remove all the excess rubber boot you can and look at the piston. If it is cocked use a large C clamp on the high side to push that side back in and try again.

Some are easy and some are a real pain.

Good luck.

I have had them get stuck and sprayed them with pb blaster and let them sit and give them some tap with a hammer. Last one wouldn't bunch then I let it go soaking and freed it up and it popped right out with some air at very low pressure.

Here's how you get caliper pistons out when they won't pop out with compressed air, or by the brake pedal.
Pump them out hydraulicly with grease.
Here's how you do it.
Get a bolt the thread size that's used to attach the brake hose to the caliper. Something not very long, just enough to thread into the caliper.
Get a grease fitting, something thats used on the ball joints tie rod ends, things like that.
Drill through the length of the bolt with whatever tap drill size the threads on the grease fitting are.
Tap the drilled hole in the bolt to accept the grease fitting.
Or even just open the bleeder screw and pump grease through that, while having a bolt in the brake hose location to block that off.
Go get your grease gun, and hook it up to the adapter that you just made. Pump away. Keep pumping grease into the caliper until the piston comes out.
Put a rag over everything before the piston pops out, or your gonna have grease all over the place.
You will be surprised how much hydraulic pressure that method will build up to get stuck pistons out.
I have been using that trick for years in the rebuilding dozens of the 4 piston Kelsey Hayes calipers that are used on the 65-72 A body cars.
Give it a try, you have nothing to loose.

I've used heat before to loosen up rust. Calipers have to be really badly pitted to not be rebuildable because the o-ring seals against the piston, not the caliper bore. On bad calipers I like to clean them and then glass bead them (actually I do that to almost every one I do).

Don't really see the savings in trying to do this yourself.

Check Advanced Auto, they have free shipping on any order over $75. I bought 2 rebuilt calipers WITH pads for $80 plus they have a lifetime warranty.