The stock transmission mount on my 75 C15 was broken, so I bought an Energy Suspension urethane replacement. When I went out to fit it, I was able to remove only 3 of the four bolts from the stock unit. The last bolt is the upper bolt on the driver's side. The positioning of the bolt prevents me from using my ratchet and I can only get a short box wrench on the bolt, but then I have no leverage and I can't break it free. Is there a special tool I am supposed to use to do this like some kind of offset wrench or a technique that I don't know?