Humming sound 55 and up

Will pinion and carrier bearings make noices if the front driveshaft is out if there bad? Or will it only make noices if it is under load from the front driveshaft? I don't hear it when the front driveshaft is out. I replaced all ujoints and centering ball. They watched it on a lift and they said my driveshaft looked out of balance. I think my splines might be bad in my driveshaft. Gonna try another driveshaft this weekend.

Pinion bearings are usually only heard under load. carrier bearings will be heard all the time.

If the noise goes away with the d/s out... its the problem.

I dont hear anything with the front driveshaft out.

Short of pushing and pulling the pinion yoke around for obvious play, if you turn the yoke by hand and feel roughness of any sort, there is something wrong. There will be resistance because of brakes, tires, etc. That's not what you're looking for. The yoke should feel smooth as glass when you turn it. If it isn't, the pinion is probably at least part of the problem. The splines on the driveshaft ought to be pretty tight. If you can move the slip joint up and down with little effort, I would lean towards that.

I tried another driveshaft and its still there. Outer Pinion feels tight and isn't leaking. Maybe its the inner pinion bearing.

I would take the differential out and check the carrier bearings. If you change them you would need to check the back lash, but if you take it out and put it back as is you don't need to. If the pinion turns smooth as glass both bearings are probably fine but if you are going to the trouble to R/R carrier bearings, I would at least check the pinion. If there is a lot of metal floating around the pinion bearings may be worn.

Took my driveshaft to the shop. Splines were bad and a little off balanced.