Hello!
Highway 199 is Jacksboro Highway, it goes all the way from Downtown Fort Worth through Azle, Springtown, Poolville, then on to Jakcsboro. Exchange is a street in North Fort Worth near the famous Stock Yards. 199 is lined with a million car repair places so it's interesting that he mentions that in the song. Jacksboro Highway had a reputation, and today to an extent, as a den of sin. As a lifelong Knopfler fan and a current Fort Worth resident it was great to hear all of this in a song! Makes me wonder if he has traveled down Jacksboro Highway like he did Telegraph Road...
Regards,
DM