Dereyk Patterson wrote:

>I have a problem with my syncro. The thing vibrates at about 45mph on 
>up. I removed the drive shaft, It checked out O.K. 

Are you sure the driveshaft was checked out properly?  Most of these
vibrations I've heard of come from driveshaft problems.

>Without drive shaft 
>installed, there is no vibration. HMMM? I checked wheel bearings, 
>replaced 1 (front) problem still persists. I check cv's, replace a full 
>set of rears (didn't need to be replaced) Problem still persists.
<snip>
>Real wheels spin, nothing happens up front. Am I correct to 
>assume that I have a problem with my front diff.......possibly my 
>viscous coupling?

Possibly.  I assume that you've re-installed the driveshaft (although you
didn't say) and that the vibration came back?  If the viscous coupling has
failed and does not transmit power to the front diff it would make problems
like yours.  Between the VC and the diff, I'd say it sounds more like a VC
problem.

> Please help, as I have just gone to the junk yard and 
>purchased a $500 used diff. I plan on installing it this weekend. 

You bought the diff without the VC?  They are bolted directly together and I
suspect most wreckers wouldn't sell one without the other.  This will sound
like a real silly question, but are you sure you have just the diff and not
the diff + VC combination?

>I also have a line on a new viscous coupling, and I don't know what the hell
to 
>do. This part by part process of elimination is pissing me off, and 
>wearing a big hole in my pocket.

Yes these parts can be quite expensive and the process quite frustrating.
 Perservere and you'll find the answer.  The "silver lining" is that for each
part you replace that doesn't cure the problem, you have a spare on hand for
future needs.

Good luck,
Jim Davis
87 GL Syncro
88 GL Wolfsburg