Anyone with thoughts here?   
      
   I have a friend who has a 2005 Buick Rainier that had rear air bag suspension   
   on it.  As seems the case, it developed a leak in one of the bags.  In that no   
   tow use would ever be made of it, the decision was made to convert it to coil   
   spring suspension.  Which, as I sort of watched the darned good fellow do   
   this, was done one side at a time with no strange axle dropage or twist   
   anywhere on the rear end.  Everything seemed to go fine.  Except that now,for   
   the first time on this 67,000 mile vehicle, there is what I am pretty sure is   
   definite driveshaft vibration that has shown up!  It starts to be of notice at   
   about 62+ MPH and then sort of vanishes at about 75 MPH.   
      
   I wonder if it was really 'there' with the air bag suspension, but was just   
   never of notice then?  The shocks were also replaced with the reccomended new   
   ones at that time to.   
      
   OK, I have a friend who has done driveshaft alignment and checked U-Joints for   
   me for about 30 years now.  Very rare need but then, I built my original   
   Austin Healey 100 with a full Chevy Fuel Injection Corvette engine in it back   
   about 1962 or so.  And that, of course, meant a full custome drive shaft for   
   the Chevy Corvette transmission to the Healy rear end.  And yes,I do   
   understand about absolute need to align the U-Joints correctly at either end   
   of the shaft.  As well, as, in theory, to get the EXACT rear end and   
   crankshaft allignment with the rear end suspension so that they are precisely   
   alike in planar mode even as the axle bumps up and down.   
      
   But obviously, in the case of this Buick I don't do that design, nor was there   
   any change in axle positioning or whatever with this job.   
      
   So .. I take the Buick to my friend.  He jacks it up.  Oops!  It has an   
   aluminum drive shaft!  I've never seen this before and he tells me he cannot   
   check, straighten it.  As well, yes, I've had drive shafts custom balanced in   
   Houston a hundred miles South of me in College Station, Texas. But welding   
   balance weights and fooling with aluminum tubing?  Hmmmmmm...   
      
   Who should I listen to as to what they tell me about this?  What are the   
   thoughts here?   
      
   Thanks!   
      
   Mike Luther @ 1:117/100 .. also N117C   
      
      
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    * Origin: BV HUB CLL(979)696-3600 (1:117/100)