Roger,

The difference IMHOP between the latter-day bluegrass version and the older blues version is the return to the four chord *.

G(1)                                          
Twas in the spring one sunny day,
            C(4)                                  G(1)
my good gal left me, lord, she went away
                               D(5)   
Now, she's gone, and I don't worry,
          C(4)*
lord, I'm sittin' on top of the world.

Chance