We need to know the specs on the turbo,A/R on the turbine housing. Compressor size, etc.
I believe they are really designed to use on diesel,so they would not be that great for a non diesel application.
What price is fairly cheap for those turbos?
If they are less than $200,, give it a shot, otherwise you can find decent used turbos for a six cylinder for $150-$400 dollars depending on your search.
Or even take a chance w/those cheap$ import turbos on Ebay?
Here is one, Ebay Item number: 120130021460
Buick GN (Grand Nationals) forums are always selling turbo's & you can find Syclone/Typhoon turbos also.
Find a Duramax forum & do a search for your questions, that might give you some answers.
MBHD
