Well, guys here is a story y'all might want to read. Last October, me and a buddy changed gears in my 90 1/2 ton Chevy pickup. It has a 10 bolt rear in it and it had 3.42 gears in it until we changed them to 3.73's. While we had the axle all apart, I decided it would be a good idea to change the axle seals at the time. I bought seals from auto-zone and installed them. (they were timkin seals I believe) Anyway, I hadn't put but maybe 2000 miles on the truck when I had to drive it from Nebraska to Illinois. On the way back from Illinois, both rear seals started leaking badly and all the gear oil leaked out of my diff. The rear end started howling very loudly and by the time I realized what had happened, it was too late. I took the axle apart yesterday and had a look around and saw that the pinion gear has damaged teeth and has started to chew the ring gear. I went ahead and replaced the seals and filled it with fluid just to see what it would do but the rearend still howls like crazy. My brand new gears and bearing are ruined. I can't believe this has happened after I tried to do the right thing and perform some preventative maintenance. The bottom and sides of the rubber part of both seals were cracked and leaking. They looked like they had 100K miles on them yet they were only 2 months old. I also had a problem with an auto-zone alternator that had a 1 year warrenty. The alternator quit after 3 months and they wouldn't give me a new one. They tested it and said it still put out the proper voltage but they never tested it under a load. I was wondering if any of you had had similar problems with auto-zone parts. The bottom line is that by saving a couple of bucks at auto-zone, they have cost me a rearend. Be careful what you buy and always save the reciepts. Anyone have a rearend with 3.73's for sale?