Went Bang! Now no go.

Happy New Year and Howdy from Southern Alberta. I have been quietly monitoring this site as it seems to be an interesting and valuable resource for Arctic Cat owners. I'm seeking opinions on a problem with my ATV. I have 2001 500 Automatic (not IRS) with 27" Mud Lights on it that stopped with bang under load. I was pulling away from a stop half way up a steep hill in low range 4WD when something went bang down below. Since then it will not turn the propeller shafts to the front or rear diffs. in any gear. The engine runs fine and I've tried rocking the machine back and forth with power on in gear to listen for grinding or chattering perhaps from the secondary drive or driven gears with no result. The belt I installed last spring is still in new condition and the moveable drive face and driven pulleys look like they function normally when I rev the engine up. Are there more diagnostic checks I can make before removing the engine transmission assembly? Suggestions? I have been studying assembly diagrams for the transmission and have the shop manusl for the machine but haven't come up with a solution yet. What do ya think?