Late model Vanagon disc brake calipers have one piston per unit. Whether your brand of caliper is ATE or Girling, as long as it is 1986-91, then this kit works for you. This kit contains components...

This front brake caliper bleeder valve fits all ATE-style calipers.  ATE were generally used from 1980-1985 but please check what you have on your van before ordering. Ref ID: 113615273A-ATE