Are they the stock 5/16" with 9/16" heads? Use a quality 6 point box wrench. If they are 3/4" heads on 7/16" bolts, it is tricky to keep wrench from rolling off the corners, trashing the bolt heads. I've always managed to get bolts out or in, and never broke a tooth on flywheel-torque conv-flexplate when prying a beefy screwdriver against them either. There has to be a way.