one thing is for certain. if their official diagnosis is a failed head gasket leading to water in the oil, leading to failed bearings, then the tech that changed the oil should have noticed the discoloration in the oil IMMEDIATELY when draining it. it doesnt take a rocket scientist to know that oil should be black, not chocolate brown. if they went ahead an changed the oil and sent you on your way, then they flat out screwed you.

 

and check your local laws about engine swaps. some states that require annual inspections will look at your motor and find out that its not original. and in most cases it is not legal to replace an engine with one from a preceeding model year.