Something to consider is the main voicing you hear from the guitar. It's what you hum when you think of the intro and it continues throughought the song.
Now, what you are hearing hear is a simple playing of a progression in E, then A, then B. Now for the fun, it follows a very similar to flow as to what is played in Goin' Down the Road & Day Tripper. Learn it and love it this little riff type of found everywhere!
Now back to Truckin'. Learn the main verse bodies first and hold off on the chorus. This is all found on the main site.
The jam picks up speed and is a roller-coaster if you make it one. Remember, vamping on an E chord for 124 measures will get boring play around with Bobby's walk-down and you'll breath new life into the jam!