Yeah D Rat, those tracta joints are "strong", but probably not that much stronger than, say, a stock M1008 (dana 60) axle shaft...
From
http://www.pirate4x4.com/forum/showthread.php?t=237896
"The 2 1/2 ton U joint style, max. static load is 3,600 foot lbs. of torque. The convel model "E" used...