New R4 A/C Compressor GM New R4 - 6 Groove Clutch 4.25" Diameter, .85" Gauge Line - Metric Threads - 8mm Pin Coil @ 12 O'Clock 15-20189 58948 57948, 15-2874, 15-50812, 15-1612, 15-50445, 15-5378, 15-2962