Just wanted to give an update on what I ended up doing about the noise problem I was having with the eaton 2-speed rear end that's in my 1960 F600. Ended up taking it to Gear Train in Charlotte, NC (I do recommend them). Needed new bearing kit plus the ring gear was worn. Pinion gear was good;however, I replaced it too to have a matching gear set. Found out, as I expected, gears are very hard to find for these trucks, new or used. After a lot of searching we located a new set in Michigan. Replaced the 13 1/4" ring gear with a 14 1/4" ring gear and matching pinion gear; this required grinding the housing a little in 2 places in order for the new oversize ring gear to fit. Everything else was the same. I was there to see old parts pulled out and see new parts installed. Worked out GREAT. Just wanted to say THANKS to you who responded to my plea for help! All of the advice I was given was correct and very helpfull. Thanks again!