MF, I have found if the bolt on the dress cowl won't budge then the impact driver won't move it either. I have to drill the head off and then you have to deal with the remnants of the thread
After you said that I thought up the idea of trying a Phillips socket with sliding t bar handle from my trusty 1/4 dr Workzone set I got from Aldi a few years ago. I found the Phillips 3 gave the most secure fit when I tested on a removed bolt and after pushing down and twisting with both hands, it started to move until success. Lucky it didn't break, such was the corrosion.
Thanks for that.
