constant grinding or metal growl sound while driving.any speed.forward and reverse.drive shaft has been repaired and new brakes all way around.any suggestions to the rear end that could be bad..no signs of any fluid leakage.

 

Bad bearing. Need to find it.

 

Add ALL the info about your truck to your sig and profile. Thanks

Noise coming from front , rear, middle? Is it a 4x4 or 2wd? Need more info, add it like I suggested.

 

im new to working with differentials.other than taking the yoke out of the diff.and checking that 1.where else are there bearing in the diff.

 

noise is coming from rear

 

1988? Anyway, 2wd. Could be diff or could be axle bearings. You'll need to check. Download a service manual from the FAQ/DIY section and get a Haynes manual also. You need to raise the rear of the truck off the ground and figure it out.