I may be wrong, but I seem to remember that sometimes in Vietnam the markers along a route give a distance to the terminal city/town of the route, as well as info on distance to various towns along the way (ie one marker may have "town X 60km" and the next might have "town Y 80km" but in addition to this there is always the km to the terminal city). I think I remember km to Hanoi was displayed on both sides of the markers for hundreds of kms in addition to various km distances to other towns. Jim would be able to say whether this is a figment of my imagination or not. I thought that the road east of Savannakhet into Vietnam has been called Highway 9 for a long time (originally named by the French?), but I don't really know. The explanation that there was once a 327 route is the simplest, and may be correct, but if so it seems a coincidence that the road name and distance to Dong Ha is the same.