I don't know, I have wondered about them also. My van is a 1990 and still has the original ball joints. Every once and awile I check them by lifting one side of the front of the van and put a long strong pipe under the wheel and try to rock the wheel up and down to see if there is any play, It helps to have an assistant. This the way I used to check most cars that were 2wd with rear wheel drive and the same type of front susp. I don't know if this is right for the vanagon. The Bentley manual does not explain how to check them. Come to think of it the Bentley manual is vague on alot of procedures. Any one out there know? I will probably change them this summer, just as a preventive measure. I think after 12 years and 174,000 miles there due. John 1990 vanagon gl