I have the same leak and would like to do a refresh also .I have changed rear seals twice over the years and think I have to do a oakie bushing ,I have also changed the transmission oil and after found the rear end a little low so I think it may have been that I did not fill were the ball is. I have a newer sm420 that I may swap as it has the rear back up light switch.keep posting your progress maybe a good time to do mine as I have been putting it off for too long
