This is such a great grinding droney tune, there are the other tunes like it, find them on one of the sites from the links page, they might be called 5Miles To Town, etc.
I believe this to be from the terrific Clyde Davenport.
Some versions have just two parts, some the three..seek and listen.
The version that caused me to question and bug the folks that actually learned this version is the two part tune. The low part get really droney, but in a good way, then there is a signal from the lead fiddle that says 'Now we're gonna play the high part two times'...then back to the low drone part.
I will link to it here eventually just to drive Andy nutz...and prove I wasn't. (It's pretty cool, I havejheard it played by some folks with Authentic Certified Olde Timey Fiddle playing credentials playing it at Fiddle Tunes in 1980, from a tape Mark Olson lent me.)..kb