So, I bought my truck a few months ago. Nice condition, well taken care of but was completely stock. I talked to previous owner and he said he had transmission built with heavy duty parts for towing and at the same time he went through and replace ring and pinion, seals, bearings in rear end at same time. I am and have done some upgrades but just want a good maintained reliable truck. Sorry I am going on and on but getting back to having rear end redone. When I changed the rear differential speed sensor today I pulled old one out and there were metal filings on the piece that sits inside the rear end. I thought maybe from before it was redone. So I put new one in and didnt put any oil on o-ring so I pulled it and put some oil on o-ring and noticed metal shavings on new sensor end. Do you think there is some wear already on new rear end or leftover from when they redid the rear end and obviously didnt clean it out very well? Not sure how that sensor is set in there to know if its from before or now? There is 10,000 miles on tranny rebuild and rear end. The only thing I have pulled is a boat and smaller trailers under 5,000 lbs.