Hydro-Gear EZT Hydrostatic Transaxle ZD-DUBB-2A7C-2XPX Zero Turn Mower. Genuine Hydro-Gear EZT transaxle, model number ZD-DUBB-2A7C-2XPX. Complete units are built to an exact configuration. Match the full model number on your unit’s Hydro-Gear label (first line) to this listing character for character. The second line on the label is the cross reference number.