My '84 Westy has a problem that makes it difficult to ride in the back 
seat.  When driving in a straight line, especially with an unpredictable 
cross wind, the back sways from side to side.  Not a lot, just enough to 
make you car sick if you are sensitive to such things.  My wife describes 
it as feeling like the van is swimming like a fish!  My '72 westy did 
this too, only much worse.  Any ideas?  I thought it might be that the 
cross wind is exerting force on the entire van, while the steering 
correction is applied only to the front, but I have never felt anything 
like this on non-VW vans.

Could it have anything to do with the tires?  They are Michelin XZX which 
are NOT reinforced.  (yes, the tires are identical front and rear)

Bill