Can you possibly shim up the bottom of your current tray? This migh allow the unit to fit. It would be slightly higher but that may not be much of an issue. In the Z-18, the tray was wide enough but actually a little too deep for my liking. I wanted to be able to easily touch the control buttoms with my toe. I shimed up about half and inch. Even higher would not have been an issue. You won't have to keep your foot on the pedal so much with the Ultrex- The replacement trays are crazy expensve and the additional cutting and fitting will be a pain.. Just a thought about it..