Paul, you most likely have the 2gm engine and you will most likely find a sign on the engine stating so. When you check the engine out look for signs of obvious leaks which should show as stains around hose and on the block. When you start up for the first time be specific with the previous owner that you want the engine to be cold. He should not start it before you arrive with the mechanic. When you first start her up check for excessive smoke from the exhaust. My engine run relatively smoke free and its 21 years old. Also check that there is water coming out of the exhaust. You can check the temperature of the water by touching it and see if the thermostat is working. It should be slightly warm. Listen for strange noises although if this is the first diesel you have encountered they may all seem strange. Your mechanic can check the electrical system to see if the alternator is working. Check the operation of the gearbox and the ease of operation of the shift controls. Good Luck
