I've managed to stop breaking them. I also have a big block too.
here is what I did.
limit suspension travel by putting fuel tube on the shock shaft.( just a little)
put a "o"ring inside each dif cup.
adjust the suspension track so the dog bone is in the center of the cup.
worked for me. I can go 5 to 7 tanks before I change them before they break.
now the dog bone is actually wearing a groove in the cup (like a dremel tool would) but only on the rear. I guess the front doesn't get much of a chance for traction up in the air all the time.LOL!