fordson super major back end trouble?? how to fix???

hello, today i was driving my fordson super major (new performance, live drive) down a field when suddenly a loud screaching noise came from the gear box area, the rear end locked up solid and the clutch packed in (presumably wrecked) and then we tried to tow the tractor in neutral but rear wheels were rotating in opposite directions to eachother??!! what could have happened (need tractor asap as it's our 2nd farm tractor)
any help greatly appreciated!!!

Gwilym Jones
January 2013