Hair dryer. Warm them up good, apply penetrating oil again, allow to cool. Hit them with the impact wrench again. If they don't open up, warm them up again and try it a second time.
A cohort over here has mentioned tapping the bolts with a hammer and punch to vibrate them loose. 50 taps to start with.
A cohort over here has mentioned tapping the bolts with a hammer and punch to vibrate them loose. 50 taps to start with.