Help Please,,Need Mule Guru's
 

I am working on a 98 Mule for a friend, and it has a problem. You will be going along and all of a sudden something starts grinding. I come to a stop,put it in neutral,,try reverse ,it also grinds, try forward again, it still grinds. I need to shut the machine off, then start it back up and it sems OK. The linkage seems ok,,,and if it was the linkage, I dont think that it would do it in both forward and reverse. The grinding is coming from the tranny. I know this unit has seen a lot of use,but it seems to do good when it is not grinding. Any and all info much appreciated.