Where do we get such a thing? Is it just an adapter bushing or something very special for this purpose?

This seems a little high!
http://www.marks4wd.com/mfc707.html


Deve

1950 Chevy 3100 Deluxe Cab
1950 Chevy 3100 Standard Cab
In the Stovebolt Gallery
The Think Tank
More info and tips at Deve's Technet