hi, i have done extensive research on this and there never was a factory turbo until early 90s and they were om601 +om602. the turbo on earlier vans were SST kits out of sweden, trueblood trv offered them as an option but they were aftermarket kits installed as part of the conversion process. kind of like mercedes benz applies no chrome to any wheels at factory,it is done at dealership. best regards, timb