One of the typical B&T slap strums is employed here - same as Delia's Gone, Myra, Angelico, Gimme Some, La Bamba, and a host of others.  To get the proper B & T effect, whenever an E chord is shown, the E chord should alternate with an E6 chord every other 16^th note. Attached is a four bar B&T type slap strum illustrating what I mean.  Often when employing the slapstrum, Bud would use one type, while Travis would use another, to complement each other.

Listen to an example of the slap strum (167k).