I did a u-joint a few years ago with a clamp that was just big enough for the job. It worked but was really difficult to turn due to the force needed. So this time I got a big 8" C-clamp from harbor freight. I thought from the looks of its size that this time it would be a bit easier. Well in short the clamp bent from the force. The actual C part of the clamp deformed so the two sides where about two inches off by the end. I don't know how I got the one u-joint back on using the clamp but it happened. It took 7 hours due to the bending of the clamp. I'm regrouping and for sure will attack the other two with a bench vise next time.

Lesson learned. U-joints are for a vise and not a big c-clamp. At least not one made in China from Harbor Freight. Due to the embarrassment of the situation, identity withheld.