What brake set up do I have ?

Theres several different calipers based on piston size and banjo fitting location

73-76 A,B,E 2.60" diameter piston
78-79 B,C 2.75" diameter piston
Both of these have the same hose fitting location, just bore size is different

Then you have 77-89 FMJ calipers. These bolt on the same way as the A,B,C calipers, but the banjo fitting location is positioned differently, also depending on the year and model the pistons are sized differently. 84-89 M body use the same 2.75" piston as the 78-79 B,C body cars

I could be wrong with some of this information. I try to be factually correct.