If you are looking for no frills, no nonsense pure Rock and Roll, Gov’t Mule is a great place to look.  Their real accomplishments are not in the studio, but on the concert circuit where their Southern flavored Blues Rock makes them a decent draw.  Although they are not always classified as a Jam band, it is when they are jamming that they really shine.  Having said that, the Hall already has the Grateful Dead and the Allmans, there is no void should Gov’t Mule not get in.