Zak says when he heard Les Gold from Detroit's "Hardcore Pawn" was selling the 1968 VW van ... he snatched it up for $32,500.
Dr. Kevorkian used the van during his string of 130 assisted suicides before his own unassisted death in 2011.
Zak also got the original registration and a copy of Jack's driver's license. The bad news ... the van doesn't run.
This is the second piece of historical gore the "Ghost Adventures" star scooped up this year ... back in March he bought the cauldron serial killer Ed Gein used to secrete dismembered body parts.
We're told Zak plans to use the van for a paranormal project.