The Bass on this whole album is hard to hear so pardon any mistakes.
I think it's on about an E flat.
                                 RUSS FARHA/ DALLAS, TX
Riff 1
A--4-4------|
E------4-4--|

Riff 2 (sounds like a standard triplet rhythm)
A-------------------------|
E--4-4-444-------5-5-555--|

Riff 3
A------------------------------------------------------|
E--0-6-5-4---0-6-5-3----000-000-6-5-4--000-000-6-5-3---|

Riff 4 (after little guitar break)
A--4-5-5--4-5-5--|
E----------------|

First chorus (spoken) =Riff 1
Second chorus (Max)
E--3----3----3----3----|

Riff 5 (Solo)
A------------------------------------| 
E--4--2-5-4--2-5-4--2-5-4--2-5-4-----| many times

Then I think it's Riff 3 a few times
Riff 6 (outro)
E--0-0-0-0-0-0-4-4-4--0-0-0-0-0-0-3-3-3---| over and over
 
Don't forget to laugh, scream, and just go friggin' balistic!!!
Enjoy! RUSS FARHA/DALLAS,TX