You'll notice that there are two different types of square taper crank arms . I you get the wrong one your cranks will be out of time. You'll need to pop the mounting bolt off again and see if your arm's square taper is standard or offset. Look at a few pics on Jenson and you will see the difference. Sorry, should have mentioned this to you earlier.
Once again, ask me how I found this out
I'd spring for one that is a little more expensive and at least looks similar to the xt. With the uphills we have at Alafia/Boyette you don't want to go with the lowest of low end.Flex and bending will be an issue. Then again I just recently broke a right crank arm on my $450+ crankset!!! Pretty sure I saw a $17 one on there that looked just like the older xt cranks. I think shipping is only 5-6 bucks.
So I assume your crank was beat up pretty bad on the back side? Or did you not pop it off for a look yet.