NEW GENUINE OEM HYDRO-GEAR ZT-5400 SERIES COMMERCIAL HYDROSTATIC TRANSAXLE. Avoid the massive drop in torque, loose tracking, or sudden failures common with rebuilt or heavily used commercial hydros. Keep your commercial zero-turn mower operating at peak performance with this 100% genuine, factory-original OEM Hydro-Gear ZT-5400 powertrain hydrostatic transaxle assembly. Built to survive the grueling daily demands of professional landscaping fleets, this heavy-duty unit features a high-displacement piston pump, a rugged internal gear reduction differential, and a massive commercial-grade axle shaft designed to withstand extreme load shifts and hill-side braking. EXACT COMPATIBILITY & CROSS REFERENCES This genuine factory commercial transaxle updates, replaces, or directly cross-references with the following part numbers. FITS SELECT COMMERCIAL ZERO-TURN RIDING MOWERS: The Hydro-Gear ZT-5400 series is the top-tier flagship transmission system utilized across the industry’s heaviest commercial zero-turn (ZTR) mower frames, including premium models from: 1. Toro (Z Master Commercial Series). Exmark (Lazer Z Series). APPLICATION REMINDER: Commercial zero-turn mowers rely on separate independent transaxles for each rear wheel. This specific assembly is engineered strictly for the Right-Hand (RH) drive side of the machine. It will not work on the left side. If you have any questions or need to verify compatibility against your exact zero-turn mower model or serial number, please drop us a message before ordering. We are happy to help!