Some of the studs in the block need to be removed and replaced. Have a good stud puller that grips the stud well, but some of them are so stubborn to the point they will break off for sure. Broke one already. Have tried heat & cooling cycles, Kroil, acetone & ATF, and plenty of patience. Probably been in there for 60 plus years. Any suggestions I should try ? Thank you Fordbarners.