Was that on a T5 conversion?

What were the final engine/transmission and pinion angles?  Did you have to raise or lower the pinion nose for your application?  Glad you got it sorted out.

I had 88.5 degrees measured at the balancer. Added a 2 degree shim  to raise the nose of the rear end. Ended up with 88.9 degrees at the pinion flange.

I used the Craftsman version of that. Looks just like it.

HI ALL.....this is all VERY interesting to me cause I have been suffering from a Vibration also, but it has a Rhythm...its an On/Off vibration that increases and decreses with speed.   

Now I also have a 69 with a T5, Ive had EVERYTHING redone mechanically...Engine, Trans Rebuilt, New Drive Shaft Made, new Yokes, 3.73 Auburn.  The thing is I also feel the Ring and Pinion was not installed correctly cause depending on Gas Pedal position with Speed It will vibrate Greater------Consistently-----Louder and with a deep grinding sound (this also happens while at higher speeds then Coasting in Neutral).

The newest occurrence over the past week was a new inconsistent sound with a vibration that resembles a new car Wheel Bearing.  It has become louder and louder with increased vibration over the past week.  I Was thinking Axel Bearings and recently Universal Joints on the Driveshaft.  I dont know exactly how to test universals, but yesterday evening I jacked uo the Rear end and Noticed movement on the wheels when I grab the tires at 9 and 3 oclock and try to rock them.  This is followed by a CLACKING noise (metal hitting metal).   Rear Left is worse than Rear Right.......What is this and Why?

Lastly, with a Auburn Limited Slip, shouldnt both wheels spin while turning one?  they each turn the driveshaft while in neutral, but the other wheel stays still.  

Sorry for all the Words, but im pretty lost when it comes to rear Diff's and their Angles and Axel Work.
regards,
Jeff

M1Mustang69 wrote:

HI ALL.....this is all VERY interesting to me cause I have been suffering from a Vibration also, but it has a Rhythm...its an On/Off vibration that increases and decreses with speed.   

Now I also have a 69 with a T5, Ive had EVERYTHING redone mechanically...Engine, Trans Rebuilt, New Drive Shaft Made, new Yokes, 3.73 Auburn.  The thing is I also feel the Ring and Pinion was not installed correctly cause depending on Gas Pedal position with Speed It will vibrate Greater------Consistently-----Louder and with a deep grinding sound (this also happens while at higher speeds then Coasting in Neutral).

The newest occurrence over the past week was a new inconsistent sound with a vibration that resembles a new car Wheel Bearing.  It has become louder and louder with increased vibration over the past week.  I Was thinking Axel Bearings and recently Universal Joints on the Driveshaft.  I dont know exactly how to test universals, but yesterday evening I jacked uo the Rear end and Noticed movement on the wheels when I grab the tires at 9 and 3 oclock and try to rock them.  This is followed by a CLACKING noise (metal hitting metal).   Rear Left is worse than Rear Right.......What is this and Why?

Lastly, with a Auburn Limited Slip, shouldnt both wheels spin while turning one?  they each turn the driveshaft while in neutral, but the other wheel stays still.  

Sorry for all the Words, but im pretty lost when it comes to rear Diff's and their Angles and Axel Work.
regards,
Jeff

   Don't know about the metal on metal noise.  But I had the vibration at highway speeds when I let off the gas and coasted in my 69.  Hit the gas and the vibration went away.  That 2.5 shim nose up took care of most of the vibration.   Steve69
 

M1Mustang69 wrote:

Lastly, with a Auburn Limited Slip, shouldnt both wheels spin while turning one?  they each turn the driveshaft while in neutral, but the other wheel stays still.  
Jeff

I have an Auburn limited slip also, 9" rear, and yes with the rear wheels off the ground, trans in neutral, both wheels spin while turning one wheel by hand.
Make sure rear brakes slightly rubbing isn't causing this condition.
Did you add the friction modifier?
What happens when you do a burnout?

I don't think the pinion angle would affect this condition.
Suggest contacting Auburn tech people and see what they have to say.

M1Mustang69 wrote:

The newest occurrence over the past week was a new inconsistent sound with a vibration that resembles a new car Wheel Bearing.  It has become louder and louder with increased vibration over the past week.  I Was thinking Axel Bearings and recently Universal Joints on the Driveshaft.  I dont know exactly how to test universals, but yesterday evening I jacked uo the Rear end and Noticed movement on the wheels when I grab the tires at 9 and 3 oclock and try to rock them.  This is followed by a CLACKING noise (metal hitting metal).   Rear Left is worse than Rear Right.......What is this and Why?
Jeff

Sorry, just re-reading this post ...
Checking the universals: get under the car, w/transmission in gear and rear brakes applied.  Twist the driveshaft and see if there is any play in the universal joint, there should be no noticeable play. 
Movement of wheels at 3 & 9 o'clock:  if by rocking you mean rotating the wheels in a forward and backward motion, the clacking your hear is likely the backlash of the ring and pinion.  IMO, it is difficult to determine if it is excessive, or not, by this method.
If by rocking you mean in and out of the axles, this would likely be the play in the side to side motion of the axles, there shouldn't be much movement in this direction.  
Putting all the symptoms you describe in this post together, I suggest that you pull the rear, something could be wrong in the Auburn unit causing the noise and vibrations.