the iwaver has a slightly bigger Potentiometer in the servo box….by ‘bigger’ I mean the that metallic, protruding knob centered on the pot. This knob is the one that connects with the first servo gear in a tube-esque alignment. THe other two servo gears are interchangeable with z ones….
In short, one of the servo gears is designed for the iwaver pot, which is bigger. Try as I did, you cannot forcibly squeeze a Kyosho gear of the same type into the iwaver pot. perhaps if you found some way of making it bigger, but the gears are so damn small.