There was a question to me I had missed in a post a while ago concerning the replacement of Z600 seat upholstery.  For the sake of information (late as it may be) here is a 'side by side' comparison of the 2017 RZR, 2013 Z600 and 2022 Z500 seats.  The comment questioned if a RZR bottom seat covering could fit on the Z600 cushion.  It appears as if the bottom part of the RZR seat is similar in overall size to the Z600 but a little thicker, so, guessing with some tugging and stapling that one could be made to work.  I cannot guarantee anything, of course, but I've at least tried to include multiple angles and measurements as a reference to judge yourself :-)