Genuine Hydro-Gear ZT-3100 hydrostatic transaxle ZL-GPEE-SNLB-2GXX. For right hand side (when sitting on the mower). Replaces Husqvarna part numbers 597561601 and 597561603 and Hydro-Gear part number ZL-GPEE-3NLB-2GXX.
Also available: Left side transaxle