We are working on the same kolpin/axis 500 configuration. Lowes sells the blade as compatible but the mounting plate is exactly the wrong size for the width of the axis 500 frame. We cut the u-bolts short so they could fit over the frame and extend down. However, the adapter plate slots to receive the u-bolts are not cut in the right place to avoid the frame. The u-bolts bind with the plate no matter what configuration we've tried.
We may try wider u-bolts or may need to modify the adapter plate. We'll try to update the thread if we find a solution.
Anybody else successful?