02 Ram 1500 grinding noise

I have a 02 Dodge Ram 1500 that I bought a few months ago, and it’s been nothing but problems. The most recent is a grinding noise I hear coming from the rear of the truck in OD at about 45 to 55mph. It happens under light load, and only does it for a few seconds or until I let off the throttle. It has trouble codes for misfire on cyl 4 and 8, and torque converter mechanical ( no rpm drop detected after lockup ).. I don’t think it has anything to do with the torque converter due to it may be possible the code is being triggered by the misfire codes. The truck has 4x4, automatic, and a 5.9L engine. Any ideas?

You should check the ujoints! Raise it to check.Wheel bearing? Pull the wheels and see if you have any rear end grease leaking. And maybe change the rear end fluid and inspect. As far as the misfire goes check plenum gasket and cat. And as usuall the plugs ,wires,injectors,vacuum leak.....etc. Does it start ok ? cold / hot etc...

Try putting in plugs in first for the missfire.Stay away from Bosch plugs and stick with Champions only.All I see is problems with Bosch plugs in Chrysler products and they go in the garbage can replaced with Champions.I seen one mistake what people do when after tightening the axle nut,leave the cotter key out and the nut loosens up due to premature wheel bearing failure.The cotter key is very important to prevent the axle nut from loosening up.

I put the correct champion plugs in the truck about 3 weeks ago. The truck ran great for about a week then it started misfiring again. I don’t think it’s the plenum gasket. I looked for pooling of oil down in the intake and didn’t see any. Engine starts great cold or hot. One thing I noticed is that it puffs smoke when started after its been sitting overnight. Its irritating cause the heads were replaced 8k ago. This should eliminate the possibility of leaking gaskets seeing how they have already been replaced with the heads.

As far as the grinding noise goes, I do have a bad wheel bearing on the front left. This has nothing to do with the noise. I don’t think its a u joint, it comes and goes and doesn’t sound like that. One thing I did notice was the pinion seal is leaking, and I’ll pull the cover off and inspect the diff when I have time. Thank you for your help and keep the ideas coming

I had this problem with my 02 and simply changed the diff fluid and that took care of the noise - I used Valvoline when I changed it if I remember correctly.... I then changed it again about a year ago (no noise, just figured would be ahead of the game this time)... A buddy of mine said he used Mobil 1 in his stuff and in his drag car... never had any problems... so I took his recommendation and used it... well, I have the noise again... I plan to change it again tomorrow, this time back to the valvoline... Don't know if that'll help or not, but its cheap and easy if nothing else to eliminate the fluid being the problem.