I had the same problem when I tried to put a new aftermarket arm and blade on my 41. I switched back to the old anco setup that was on the truck when I got it (its an aftermarket but its probably from the 80's). Anyway the arm from center of where its mounts to the cab to the center of the wiper blade mount is 10.5", the blade on mine is 8.25", and the overall tip of the blade to the center of where it mounts to the cab is about 14.625". The blade on mine swivels a few degrees on the arm too, so when the arm sweeps to the far extents (full L&R) the blade turns some and gets almost parallel to the center divider. The new one I got didn't swivel but overall it is almost exactly the same dimensions. Hope this helps, I'm home sick today, so if you need more measurements, let me know.
Rob
