Chevrolet Repair: Chevy Transmission, differential gears, chevy suburban

Question
I have a 93 chevy suburban, 350 TBI, Automatic trans with OD.  There is 280,000 KM on original engine and trans.
I have a whining noise that I have noticed on the highway.  It happens only when I let go of the gas or press the gas again to accelerate.  It seems to occur only during those few seconds when the drive train is slackened due to no drive pressure from either the engine or rear wheels.  Both universals have been changed 2 years ago and also the differential gears were replaced 2 years ago.  I will have these checked again but I thought this new noise may be the sliding yoke?  If so, I assume both tranny shaft and sliding yoke will need to replaced. Is the shaft in the tranny replaceable separately from the tranny itself or does the whole tranny need to be replaced?

Thanks for your help
Ed

Answer
hey,

 Sounds like the pinion bearing.  If the pre-load on that bearing wasn't set properly when the gears were done it will burn out a bearing in no time.  Pinion bearing pre-load is set with a collapsible sleeve and breakaway torque.  Guys get lazy and re-use the sleeve or just tighten the pinion and kick it out the door. Run it in the air with a stethoscope on the nose of the rear diff.

Wayne