What Calipers

I was rebuilding my calipers and found that the pistons are rusted in patches on the sides. I plan to order some calipers. Will 76 A-Body calipers work on my 74 Duster? I have slider calipers right now, are all 76 A-body calipers sliders, or is there a possibilty of ordering pin-type without knowing it? I understand the 76 calipers have a larger piston and are a good upgrade. Are the Phenolic Piston's a bad thing(do they bind or warp???)? Or should I ask for Steel? Best place to order these?
Thanks