You're correct, I knew 76 was different and I thought 75 was also.
The calipers from just about any Mopar from 73-85 will bolt up except the cop car/taxi brakes which need the bracket to work and a few of the larger cars, the difference being is the bleeder and brake hose location, the rotors are also the same. These rotors are also the rotors that most street rod builders use to get 4 1/2" bolt cir. my disc conversion on my 50 Merc uses these rotors with GM calipers.