Mondy (V6) brakes are four stud 278mm, 94-2000.
2000 onwards were 5 stud and 300 mm.
To further confuse matters there were also some 260mm ones fitted between 97-2000 which were 4 stud.
283mm discs were never fitted to mondy but to 2wd sierra cossies, 3 door, rs500, and 2wd sapph.
The mondy brakes V6 278 mm 4 stud should go on no trouble maybe just a washer needed to space away the caliper mount away from hub a little.
tabetha