there is no easy way to test compession in a duramax motor so forget that one. service records and ask to see them , shouldnt be a problem to get if its a GM dealer and the service DEPT is open. then ask if it still has a warenty left. 5 years-100000 mile on the basic motor and 7 years-200K on the injectors and you most likely will need aset of injectors around 100K .
93 c-2500 6.5td,96 6.5td x cab,01 GMC lb7 Xcab ,2004 lly crew cab ,2006 lbz crew cab,honda CBR1100xx,2003 polaris prox 700 , 2001 31' holiday rambler 10K lbs house on wheels!