Probably popped a front axle - but also could be several other items in the front drivetrain. The axles aren't that expensive and I got to where I could change one in about 20 minutes, just that the final drive is pretty heavy and awkward. It's very difficult to tell which axle is broken by spinning a wheel unless the break is rough enough to "growl" a little when you turn it by hand. Out of the 10 or so axles I've broken in mine over the last 7 years, it seems the left one broke more often. I have also broken 2 countershafts in a final drive - same symptoms as a broken axle. Once you get the final drive off the tractor you can check it by hand if you see that your axle is good. The one other thing that happened to me was the studs for the ring gear in the front differential broke - same symptoms as the other items above. Luckily it didn't break anything else and the repair wasn't expensive, just time-consuming. I keep a new axle and countershaft on hand for mine at all times, Galen on here can get you the parts you need when you find out what's broken.