If you replace only the front sway bar you will get massive under steer.
You need to replace both the front and rear sway bars together for
balanced, safe, handling.

The Addco bars are 1" front and 7/8" rear and were the only ones available
when I bought mine 11 years ago.  The difference in this and stock is
simply amazing.  I also have Koni Red Heavy Track shocks (82-2100 and 82-
2101) which I like better than any other brand for the 2WD Vanagon.  The
Konis are adjustable for rebound but not compression so firmness and
control can be adjusted without increasing harshness.  This might not be
the optimum adjustments for a racing shock but it sure is great for street
comfort with control.  These two modifications, with stock springs, are,
in my opinion, the optimum road suspension for a stock height 2WD Vanagon
Westfalia Full Camper giving crisp, comfortable handling and a smooth ride
under most all conditions.  I also have 215/65r16 Load Index 98 tires.