"Also, I've heard of a different P/N for right and left struts."

"with or without rear window wiper"

When I bought mine from my FLAPS there were the two types listed for 
Vanagons with rear wiper.  One of the numbers was the same as used for both 
sides of the non-rear wiper vanagon.  My Vanagon has the wiper.  The clerk 
had the one in stock for the non-rear wiper, but not the other.  He checked 
the parts book addendum, and the odd strut was discontinued and cross 
referenced into the stocked strut.  I bought the pair with the option of 
returning them if they didn't work.  However, they work just fine.

Mike