I'm looking for dual piston calipers for my 79 trans am, (rear) were can I

[Jose G]

find a pair? I already have disc all around but I need more power.

 

[Goatman]

You are probably looking at aftermarket kits for dual piston calipers all of the factory ones were single piston for that year car..
I would check some of the aftermarket brake MFGs like Stainless steel brakes. Classic performance products, and others