It's Tuesday, April 24.  I had hoped to be on the road tomorrow morning.  Today I took the truck in for a lube, oil, and safety inspection.  The slight vibration I've been feeling has come from some worn out front end parts.  The garage will do the replacement tomorrow (I hope) and I'll be able to leave Thursday.  Major expense though.  The mechanic said I was OK for another 1000 or 1500 miles.  Of course I'm looking at 2500 to 3000 miles again this trip.  Better safe than sorry.