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. 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. Today 
(Valentines day) We got snow, and I got stuck ( I forgot to mention that 
I just bought this thing. I'm familiar with 2wd Vanagons. Never owned a 
syncro) 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? Please help, as I have just gone to the junk yard and 
purchased a $500 used diff. I plan on installing it this weekend. 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.

Dereyk Patterson