Hello , my 99 el dorado recently ran hot at 77000 miles. I don't know how hot and don't know a lot about engines but believe the head gaskets blown , coolant can be seen in the oil . I was told that I could replace the engine with the engine out of my 03 deville that has been deemed un fixable due to electronic problems . It would crank but not stay cranked . The engines are the same so I am told but does anyone know of any other reasons or problems I am going to run into trying to swap these engines ? any advice much appreciated . Thanks !