I was pulling an I beam grading my driveway with my 84 Big Red 200 and it was running and shifting fine. I stopped for a second, put it in neutral, then when I put it back in gear to go it wouldn't go it just made a clicking/grinding kinda noise. The motor sounds fine, the noise sounds like it's coming from behind the engine. Any ideas what could be the problem and how much it would cost to fix it.