You get off I-35 about two miles south of "The Boondocks" then, it's almost worth the trip up if you've got a little extra time. Exit 144, if I remember correctly. Haven't lived there in 15 years now, but it's a pretty nice place, I worked at the Amoco on the west side of the overpass, my grandparents ran the motel on the east side.
btw, when I moved away, 20 ended in a cornfield about a half mile off of I-35 to the east.