After market front disc conversion rotor replacement

[Bronk74]

What year blazer k-5 should I use when searching for replacement rotor?

 

[EPB72]

So GM conversion ,, ? The hub and rotor are ford to keep the 5x5.5 wheel bolt pattern GM hub and rotor would be a 6 bolt pattern ,, generally 76 - maybe 86? F 150 and bronco , for a rotor replacement

 

[Broncobowsher]

Correct, find a FORD rotor. Any half ton (except the 3-bolt lockout from '86-89(?)).
Just say you need a Brake rotor for a '78 Bronco. That should be a safe bet in any of the parts store computers.