Intro: (played 4 times) 

intro lead riff                                  repeat 4X
|--(8)\6---------------------------(8)\6------------------|
|--------8-------------------------------8----------------|
|*---------10--8--------------8------------10--8---------*|
|*----------------10~~~-------8-------------------10~~~--*|
|------------------------8h10-----------------------------|
|---------------------------------------------------------|

4x 
|--------------------------------|------------------------------------------
|--------------------------------|---8------------------8-------------------
|*-------------8-----8---10-----*|---8-10--------10-----8-10--------10------
|*-------10----8-----8---10-----*|-----10----10--10-------10----10--10------
|--------10----------------------|-----------10-----------------10----------
|--------------------------------|------------------------------------------
    "When I woke up this mornin.."
 
and for the rest of the song, billy use a lot of Quart(4) Doublestop 
Riffs, who`s a ZZ Top trademark. Like this 
  Eb4  F4     Bb4 
E|---------------------I(Bass plays C pedal Tone over Eb4 + F4 ) 
B|---------------------I 
G|-8----10-----3-------I 
D|-8----10-----3-------I 
A|---------------------I 
E|---------------------I 
 
 
              Eb4                   F4 
1.Verse: When i woke up this morning 
               Eb4                 F4 
         i was feeling mighty good 
            Eb4                                 F4 
         my baby understood, had to do what she should 
         Eb4                      F4 
         lying near a pile of wood 
         F5               Eb4 F4 
         laying on it some 
         F5                 Eb4 F4   G5 
         playing with it some        when i  
         G5                  Eb4 F4 
         i woke up with wood 
               Eb4                                 F4 
2.Verse: i was lying there thinking ´bout basketball 
         Eb4                        F4 
         trying not to lose my mind 
         Eb4                                     F4 
         my baby come to help and i let out a yell 
         Eb4                       F4 
         she grabbed me from behind 
         F5               Eb4 F4 
         laying on it some 
         F5                 Eb4 F4   G5 
         playing with it some        when i  
         G5                  Eb4 F4 
         i woke up with wood 
         Eb4                            F4 
3.Verse: beauty queens fall into trances 
         Eb4                       F4 
         debutantes lose their furs 
         Eb4                                  F4 
         but it felt so good from where they stood 
                   Eb4                      F4 
         they were working on a pile of wood 
                  F5               Eb4 F4 
         laying on it some 
         F5                 Eb4 F4   G5 
         playing with it some        when i  
         G5                  Eb4 F4 
         i woke up with wood