Former owner had backed down a steep slope, worked on a tree, went to take off and as it started moving , something popped and he started rolling back down the hill. Sounds like axle BUT may not be . IF 2-sp. was not fully in and jumped out or broke when he took off that would be same noise. 2-sp. fork could be broke off.
I turned the driveshaft by hand and it aint hooked to anything----- no drag at all and no noise either.

"A machine you build yourself is a vote for a different way of life. There are things you have to earn with your hands."