Pretty tight with the steering box in the way for hammer blows and grinders. We had to grind down a regular L shaped Allen key to get in there for at least one of those bolts. Maybe you could get one of those bits as pictured above on the head and use a prybar to apply pressure to the bit while you turn the bit with an open end wrench. I have a set of those bits and mine have flats on the out side for a wrench, they probably all do. Maybe hammer the prybar you have held against the bit...might give it enough bite doing that + holding pressure on it while turning. Maybe a die grinder would work, but there is hardly room to put your hand in there. How hard is it to drop the steering box down abit....I think there is 4 bolts accesible from the drivers side wheelwell....easier than lifting the engine a few inches.