Andy may be busy. (Not to mention a bit dizzy, he spun his car twice during the AutoX. He still said he was having fun.)
Anyhow, the April 28th event is at the GM Plant in Wentzville, MO. Essentially West of St. Louis on I-70

That big grey blob is the GM plant. There are two ways to approach. If you are coming in on 70, take the highway A exit (Lake St. Louis I think and essentially head north relative to the interstate. It will be the big factory on the left. Not all gates will be open, but if you get that close you should find it.
If you are taking 40W, you can take that to MO Highway A. Once you cross I-70, begin to look for A. Turn right on A. It will be the big factory on the right
HTH
TB
who wont be there on the 28th