Builder died

Some pics of your spindles would help identify what you have as well as a rotor diameter. My guess is he got a later model donor. So parts for any 73 & up 8 cyl dart should be fine . The trick comes in with , what diameter rear wheel cylinders? Is it the right master cylinder? Manual or power brakes? What proportional valve is fitted? You'll likely have to measure and confirm all these to have everything work together properly. When I did mine, i just ordered everything for a 75 Dart Sport with manual brakes. Since that was the donor. I also fitted the prop valve from the same vehicle.