Lang Tools TU-32-6 6.6 L GM Duramax Diesel Fuel System Test Kit Diesel fuel pressure and vacuum testing on GM 6.6L Duramax engines Gauge assembly with 6-ft. hose and quick coupler 3-1/2" gauge reads 30 inHg to 15 PSI Diesel fuel pressure and vacuum testing on GM 6.6L Duramax engines 3-1/2" gauge reads 30 inHg to 15 PSI