So about a week ago I bought a 1980's Bianchi Sport SX at a garage sale for $50, it needed a tune up, tires and tubes... So I got all of that stuff taken care of but something just wasn't right. I took the Bianchi back to the place where it was serviced and they take a look at it and realized the back axle is broken in two. They don't carry a replacement and don't know if they can get one... Can anyone point me in the right direction?

It is a 6 speed - Shimano 105 and it needs a new axle set or Hub w/ Thread-on (free wheel).

Thanks in advance