The Hustler OEM 607478 Grease Relief Fitting is an expertly designed and integral part of the Hustler Greaseable Spindle Assembly. It effectively prevents over-greasing and ensures that your Spindle Assemblies are fully greased. With the Hustler 607478 Relief Valve, grease pressure is released from the side of the Spindle Assembly, preventing the buildup of pressure that can damage the outside seal of your sealed roller bearings. This also prevents dirt and debris from entering the roller bearing balls, ensuring smooth and efficient operation. The Hustler OEM 607478 Pressure relief Valve is used with the Hustler Commercial Spindle Assemblies 607407P & 607408P that are used on the Hustler Commercial X-ONE, X-RIDE, Super Z, Super Z HD, Diesel Z, Super S, Super 104, Super SF and Super 88 Series Mower Decks. Please Refer to the Images above, Special Notes and Help Links below to ensure a proper fit. Click on the Part Numbers and Help Links to be redirected. CLICK ON ASSOCIATED SPINDLE ASSEMBLY LINK BELOW TO BE REDIRECTED TO INDIVIDUAL PART REFERENCES 607407P - Right-Hand, Standard or Common Mower Blade Spindle Assembly (Used on Side & Rear Discharge Models) 607408P - Left-Hand Mower Blade Spindle Assembly (Used at Select Locations on Rear Discharge Mower Models - OEM Mower Blades and Spindle Ass. are Painted Red to Determine the Difference) REBUILD HELP LINKS Spindle Part Number 607407 & 607408P - https://www.youtube.com/watch?v=eV76B6zpdH4 Specification Product Number: 607478 Brand: Hustler Length: 0.40 IN Width: 0.40 IN Height: 0.50 IN Weight: 0.030 LB Model Fit: * 607478 May Be Used on Additional Models/Families like Deisel Z & X-One Models - Due to Lack of Information and Details - Hilly Ridge Will Continue to MANUELLY Improve the Model Fit Chart with Time - If you Have any Questions on Exact Fit Feel free to Message or Call us. X-ONE - Side & Rear Discharge Models (Models 2011 and Later are Listed - Models Listed Prior To 2011 May Not Be Listed If Applicable) Models are Currently Not Listed Will Be Eventually X-RIDE - ALL MODELS 944074, 944868 Super Z - Side & Rear Discharge Models (Models 2011 and Later are Listed - Models Listed Prior To 2011 May Not Be Listed If Applicable) 929927, 929935, 929943, 929950, 930024, 930065, 930875, 931048, 932012, 932020, 932038, 932046, 932053, 932061, 932129, 932137, 932970, 932988, 933457, 933929US, 934216, 934224, 934232, 934240, 934265, 934273, 934281, 934984US, 934992, 935007, 935015US, 935023, 935031, 935049, 935056US, 935064, 936872, 936880, 936898US, 936914, 936922, 936930, 936948US, 936955, 936989, 937714, 937722, 937730, 938985, 938993, 940031, 940049, 941138, 941146, 941153, 941161, 941179, 941187, 941195, 941203, 941377, 941385, 942342, 942771, 942763, 942805, 942813, 942821, 942839, 942854, 942862, 942870, 942888, 942896, 942912, 942920, 943852, 943860, 943878, 943886, 943894, 943910, 943928, 943936, 943944 Super Z Hyper Drive - Side & Rear Discharge Models (Models 2013 and Later are Listed - Models Listed Prior To 2013 May Not Be Listed If Applicable) 932145, 932152, 932160, 932178, 932186, 932996, 933002, 934315, 934307, 934323, 934349, 934687, 934695, 934919, 934927, 934935, 934943, 934950, 934968, 934976, 936997, 937003, 937011, 937029, 937037, 937045, 937052, 937110, 939561, 939579, 939587, 939595, 941229, 941237, 941245, 941252, 941260, 941278, 941286, 941294, 941302, 941310, 941534, 941542, 941559, 941567, 942219, 942227, 942235, 942243, 942250, 942359, 942961, 942979, 942995, 943001, 943019, 943027, 943035, 943043, 943050, 943068, 943951, 943969, 943977, 943993, 943985, 944017, 944041, 944025, 944033 Diesel Z - Side & Rear Discharge Models Models are Currently Not Listed Will Be Eventually Super ATZ No Listed Model Numbers Super 104 Models are Currently Not Listed Will Be Eventually Super S Models are Currently Not Listed Will Be Eventually Super SF Models are Currently Not Listed Will Be Eventually Super 88 936617, 939546 Not sure if this is the correct part? Contact us with your Hustler model and serial number and our parts team will verify fitment before you order.