[V8] Howling Sound, Chap 2

[Stafford, Kenneth A.]

So, my last month reported driveline howling (consensus was center driveshaft
bearing/joints) has changed!  Yesterday, while slowing down on freeway, heard
a load snap and then continued grinding noise as I coasted to a stop.
Thinking I needed to get off the freeway...and since I didn't see a puddle of
oil or bunch of parts on the road--I cautiously drove further.  It makes no
noise as long as under load--just when you are back-driving the engine.

So 16 hrs later, I have replaced the driveshaft with the one from my parts
car--all looked good although the front CV joint was quite loose. The news
now is that the whine/howl is gone, but the grinding is still there.  As long
as you drive such that the instantaneous mileage stays below 40 mpg then it
is quiet, as soon as you let off further the grinding starts again.

So...once again I'm think rear diff and perhaps a problem with the pinion
gear shaft--the load vs unload would produce different thrust loads on this
shaft.  Any other thoughts?  It is definitely driveshaft frequency and sounds
to be coming from the back half of the car.  

I will plan on putting in the parts car diff tonight/tomorrow morning and see
what happens... 

Ken