2002 F250 Rear End Rebuild
 

Please advise on a few things:
1. I recently had the pinion bearing replaced, and now the truck whines loudly at certain speeds. I've heard mixed answers on whether I just need new gears for it or a complete rebuild kit with another new pinion bearing and gears. I just want to get rid of this awful whine. Any ideas?

2. I'm trying to find the original rear end gear ratio. The vin sticker is partly illegible.... Whats the next step?

3. Any recommendations on brands of gears and/or rebuild kits?

Thanks!

Firstly take it back to shop who did the pinion bearings. They need check the mesh again. As long as the stock gears weren't damaged, they should be as quiet as they were before. However if they did get scarred/marred or any other term you can think of, then it would be best to replace the gears. AAM is one of the bigger gear manufactures, they produce gears for motive, yukon, GM, Ford, and many others. However there are levels to the gears and those level determine how noisy they are. Richmond got a rep a few years ago for being noisy, Motive's Performance Line has been good for me. Yukon and precision gear have a decent rep as well.

There was a tag on the diff as well. However, if you jack the rear up and spin the tires you can count rotations. Mark the tire and the drive shaft, count howmany times the driveshaft rotates for a full rotation of the tire. Normal ratios are 3.73 or 4.10, so either the DS will spin just short of 4 times or 36 degrees more than 4 times.

Stock, your truck came with a 3.73, 4.10 or (FAIRLY RARE) a 4.30 gear ratio.

I agree, you should take the truck back and have the shop that installed the new pinion bearing check their work. It may be as simple as a failing U-joint.

I too agree that you should take it back, They may have incorrectly installed the pinion bearings by tightening them with a impact gun, which will destroy the new bearings in short order. While they have it apart just ask them to check the ratio.