GMC Repair: Water getting into oil, losing coolant, head gasket

Question
I Have a 2000 Yukon Gmc , I have been losing coolant for some time and have not been able to find any leaks. I am now getting water into my oil. The car does not smoke and runs very smooth. My question is where are all the possible places water can get into the oil. I know the head gasket is one obvious place. I did pull the intake , all ports are dry except one , it has oil like sludge inside it, but does not appear to have water mixed. Would that possibly indicate a leaking head gasket.

Answer
I would lean more towards the water jackets in the head or block being cracked. When you have water in the oil, the first thing I would do is a compression test, as you did, pull the intake.

If you do have to replace the block and looking to save some money I would go to Pull A Part. You can get an engine for an average price of 175.00