This is a Snapper Massey Pulley Drive. Models are shown below. May be red or black. Part No. 14738 or 7014738 (14C)

Snapper R5000 - Snapper Rear Tine Tiller, 5 HP, Series 0 - Engine & Drive Parts
Snapper R5001 - Snapper Rear Tine Tiller, 5 HP, Series 1 - Engine & Drive Parts
Snapper R5002B (85220) - Snapper Rear Tine Tiller, 5 HP, Series 2 - Engine & Drive Parts
Snapper R5002R (85027) - Snapper Rear Tine Tiller, 5 HP Wisconsin Robin, Series 2 - Engine & Drive Parts
Snapper R8000 - Snapper Rear Tine Tiller, 8 HP, Series 0 - Engine & Drive Parts
Snapper R8001 - Snapper Rear Tine Tiller, 8 HP, Series 1 - Engine & Drive Parts
Snapper R8001S - Snapper Rear Tine Tiller, 8 HP, Series 1 - Engine & Drive Parts
Snapper R8002 (85226) - Snapper Rear Tine Tiller, 8 HP, Series 2 - Engine & Drive Parts
Snapper R8002B (85228) - Snapper Rear Tine Tiller, 8 HP, Series 2 - Engine & Drive Parts
Snapper R8002BE (85230) - Snapper Rear Tine Tiller, 8 HP, Series 2 - Engine & Drive Parts
Snapper R8002S (85237) - Snapper Rear Tine Tiller, 8 HP, Series 2 - Engine & Drive Parts
Snapper RT5 (85220) - Snapper Rear Tine Tiller, 5 HP, Series 2 - Engine & Drive Parts
Snapper RT5X (85027) - Snapper Rear Tine Tiller, 5 HP Wisconsin Robin, Series 2 - Engine & Drive Parts
Snapper RT8 (85228) - Snapper Rear Tine Tiller, 8 HP, Series 2 - Engine & Drive Parts
Snapper RT8S (85230) - Snapper Rear Tine Tiller, 8 HP, Series 2 - Engine & Drive Parts
Snapper Y30080 (88027) - Snapper 30" Walk-Behind Mower, 8 HP, Series 0 - Drive Disc, Engine
Snapper Y30081B (80168) - Snapper 30" Walk-Behind Mower, 8 HP, Series 1 - Drive Disc, Engine
Snapper Y30120 (88038) - Snapper 30" Walk-Behind Mower, 12 HP, Series 0 - Drive Disc, Engine
Snapper Y30121B (80169) - Snapper 30" Walk-Behind Mower, 12 HP, Series 1 - Drive Disc, Engine
Snapper Y41120 (88048) - Snapper 41" Walk-Behind Mower, 12 HP, Series 0 - Drive Disc, Engine