Strut Dissasembly - help

Who knows how to get the top nut off the strut shaft? I need some kind of tool to allow me to put a 10mm socket on the shaft while turning the 21mm nut on the same shaft. The problem is it's all down in a hole in the houlsing. I can't find the tool that Haynes shows. Any ideas?
I could probably get the nut off with air, but that would leave me no way to torque the nut on the new strut.
Thanks, Brad

Never mind, I figured it out. For anyone else with this problem, here's how I did it. I used an impact wrench to remove the bolt from the old strut. Then use the impact wrench on low setting to put the nut on the new strut, and stop when the nut contacts the housing. Once the nut is up against the housing, there is enough resistance that the strut shaft doesn't turn anymore, so you can use a torque wrench to put 75 ftlbs on it. I used one of those rubber-strap pipe wrenches to hold the housing.