I'm doing this job right now and found two ways to help get that last bolt out. First is to pry the engine over to the left to give more room from the side firewall. I used a hydraulic porta-ram with the wedge attachment and placed it between the exhaust manifold and frame rail. I was able to get almost an additonal inch of clearance. Second is to cut down a 5mm hex bit so just a 1/4 inch protrudes from the bit holder and use a 1/4 inch u-joint and extension with a socket wrench. I'll post pictures if anyone wants it.