Please note that this is the way I play the bass line to the song. Sounds right to 
me and i even played it this way for my College Solo performance and had no criticism for it.

Standard Tuning

Also take into consideration, the rhythms during the different parts of the songs

Horn intro converted to bass
|----------------------------------|
|-------9-----------6----------5-4-|
|---6-9----------656----22-525-----|
|-7--------44-767-----33-----------| X2

Bass fill after the horn intro
|-11--11---------|
|---11-----------|
|---------9------|
|----------12119-|

Verse 1
|--------------------------|---------------------------|
|---9-----6-----5-----421--|---9-----6-----5-----4---3-|
|--9-9---6-6---5-5---4---4-|--9-9---6-6---5-5---4---3--|
|-7---7-4---4-3---3-2------|-7---7-4---4-3---3-2---1---|

Pre chorus
|--------------------------------------|
|-----------------3/13-----------------|
|-776655445566-67------77665544567-79\-|
|--------------------------------------|

Chorus X2
|---------589--------------|
|---9----6-----9-----------|
|--9-9--8-----7-76\44-7899-|
|-7---7--------------------|

Horn/Bass/Guitar Harmony 
|----------------------4678--13--11---------------------|
|---------6---------46---------13--11-13-119---119----9-|
|-----6----9---2-456------------------------119-----11--|
|-7--7-9-9---24-----------------------------------------|

Now the hard part
|-86464-4-----------------------------1414-1-1--------|
|------6-646-64-4-------------------14------4--414-44-|
|--------------6-6-6464-4242------24------------------|
|---------------------------42--24--------------------|

Verse 2
|--------------------------|--------------------------------|
|---9-----6-----5-----421--|---9-9-----6-----5-5-----4----3-|
|--9-9---6-6---5-5---4---4-|--9-9-9---6-6---5-5-5---4----3--|
|-7---7-4---4-3---3-2------|-7-----7-4---4-3-----3-2----1---|

Pre chorus
|--------------------------------------|
|-----------------3/13-----------------|
|-776655445566-67------77665544567-79\-|
|--------------------------------------|

Chorus X2
|---------589--------------|
|---9----6-----9-----------|
|--9-9--8-----7-76\44-7899-|
|-7---7--------------------|

Chorus like this X2
|-----------589--------------|
|---9-9----6-----9-----------|
|--9-9-9--8-----7-76\44-7899-|
|-7-----7--------------------|

Horn/Bass/Guitar Harmony 
|----------------------4678--13--11---------------------|
|---------6---------46---------13--11-13-119---119----9-|
|-----6----9---2-456------------------------119-----11--|
|-7--7-9-9---24-----------------------------------------|

Now the hard part
|-86464-4-----------------------------1414-1-1--------|
|------6-646-64-4-------------------14------4--414-44-|
|--------------6-6-6464-4242------24------------------|
|---------------------------42--24--------------------|

Chorus like this X4
|-----------5-585-------------------|
|---9-9----6-6---6----9-------------|
|--9-9-9--8-------87-7-7-76\44-7899-|
|-7-----7---------------------------|

(Use Stevie's voice to cue you into playing the chorus differently)

Chorus like this X2
|-----------589--------------|
|---9-9----6-----9-----------|
|--9-9-9--8-----7-76\44-7899-|
|-7-----7--------------------|

Horn/Bass/Guitar Harmony 
|----------------------4678--13--11---------------------|
|---------6---------46---------13--11-13-119---119----9-|
|-----6----9---2-456------------------------119-----11--|
|-7--7-9-9---24-----------------------------------------|

Now the hard part
|-86464-4-----------------------------1414-1-1--------|
|------6-646-64-4-------------------14------4--414-44-|
|--------------6-6-6464-4242------24------------------|
|---------------------------42--24--------------------|