I just dropped the oil pan to do the rear main seal (again) and you guessed it......coolant in the oil. The last time I dropped the pan a few weeks ago there was no sign of coolant. I had suspected a cracked head because i was losing coolant for quite some time but I never saw anything in the oil and I even went as far as doing a block test which came up good. I'm guessing coolant may have been burning off in the exhaust or combustion chamber but now the leak crack has gotten worse. I'm a bit concerned about dropping a new head on an engine that has 140k but the rear main bearing did look to be in good condition, the oil pressure is good and there's no strange noises coming from the engine. Should I just go for it? Which would be best, the new casting from clearwater or a rebuilt tupy? Thanks!