NO, it will not fit the Polaris mount.  The Polaris mount is 3" X 4.75".  The Warn 45 is 3' X 6.61".  The only place I know that has a RZR mount plate is Hunterworks.com. any Warn above 3000#.   They have a mount that will fit either mount pattern.  $99.99.

I just finished mounting an R/T 40 on my 09 RZR with this mount.