This is a A-MSR556 Trans Disc: 9.25", organic, solid PN: MSR556Main Description As Following : A-MSR556 Trans Disc: 9.25", organic, solid P.N: MSR556 Spline Count: 19Spline Diameter: 1.594" Replaces: MSR556-RO WHITE TRACTOR , 2579 WHITE TRACTOR Found in Section & Models : Clutch Parts > Single Clutch, White/ Oliver/ Mpl Moline TRACTOR: SUPER 77 (S/N <6502), White/ Oliver/ Mpl Moline TRACTOR: 77 (S/N <6502), White/ Oliver/ Mpl Moline TRACTOR: 770 (S/N <6502) Associated Items : New Also A-FRM-IHOL, A-OL-O-SUP7788, A-OL-P-SUP7777, A-OL-S-3VOLUME, A-SMO201, A-FRM-IHOL, A-OL-O-77, A-OL-P-SUP7777, A-OL-P-77, A-OL-S-HYDR-LEC, A-OL-S-3VOLUME, A-OL-S-667788, A-SMO201, A-FRM-IHOL, A-OL-O-770, A-OL-O-770880, A-OL-P-770-880, A-OL-S-3VOLUME, A-SMO201 And : Spline Count: 19 Spline Diameter: 1.594"