Transmission  Gasket Set Fits Troy Bilt Horse I , III & OPC Tillers 

Fits Horse I (SN: 1001 to 639999), Horse III  (SN: 640000 to 855638) & Horse OPC (SN: 855639 & Above)
See Below for List of parts this Kit includes. 
Quality Aftermarket Parts 

Includes the Following:
1 x GW-1123      Top Transmission Cover Gasket
2 x GW-1129-1  Tiller Housing Cover Gasket 0.010 Thick
1 x GW-1129-2  Tiller Housing Cover Gasket 0.030 Thick
2 x GW-1124-2  Front/Rear Bearing Cap Gasket 0.010 Thick
2 x GW-9604      Pinion Bearing Retaining Plug O-Ring