Mxtabs [http://www.mxtabs.net]
Band - Guns N' Roses
Song - Knockin' On Heavens Door
Album - Use Your Illusion 2

Notes:
Slash plays this song on a double neck SG and uses the 12 string neck in the verses
but i did my best to tab it all for a 6 string guitar

Tuned half a step down

h - hammer on
p - pull off
b - bend
x - scratch
/ - slide
~ - let ring / sustain
pm - palm mute
> - pick scrape towards bridge
< - pick scrape towards headstock

intro (Slash)
    G          D           C
eb|-3----3-------2-0-2----------0-------|
Bb|-3-----3-3---3------------1------1---|
Gb|-0------0---2-------0h2--0------0--0-| x2
Db|-0------------------0h2-----2--2-----|
Ab|-2----------------------3-----3---3--|
Eb|-3-----------------------------------|

intro part 2 (Slash and Izzy)
    G5     D5     C5           G5     D5     C5
eb|---------------------------------------------------|
Bb|---------------------------------------------------|
Gb|--------7--77--5--55-5xxx----------7--77--5--55~~~-| x2
Db|-5--55--7--77--5--55-5xxx---5--55--7--77--5--55~~~-|
Ab|-5--55--5--55--3--33-3xxx---5--55--5--55--3--33~~~-|
Eb|-3--33----------------------3--33------------------|

verse (Slash)
    G          D           C
eb|-3----3-------2-0h2----------0-------|
Bb|-3-----3-3---3------------1------1---|
Gb|-0------0---2-------0h2--0------0--0-| x4
Db|-0------------------0h2-----2--2-----|
Ab|-2----------------------3-----3---3--|
Eb|-3-----------------------------------|

chorus (Slash and Izzy)
    G5     D5     C5           G5     D5     C5
eb|---------------------------------------------------|
Bb|---------------------------------------------------|
Gb|--------7--77--5--55-5xxx----------7--77--5--55~~~-| Izzy x4
Db|-5--55--7--77--5--55-5xxx---5--55--7--77--5--55~~~-| Slash x1
Ab|-5--55--5--55--3--33-3xxx---5--55--5--55--3--33~~~-|
Eb|-3--33----------------------3--33------------------|

Slash plays this once then plays.....for the rest of the chorus...

eb|---------------------------------------------------------------------------|
Bb|---------------------------------------------------------------------------|
Gb|--------7-77b--5-55b---5-5-5---------7-77b--5-55b~~---------7-77b--5-55b~~-| x1
Db|-5-55b--7-77b--5-55b--5-5-5---5-55b--7-77b--5-55b~~--5-55b--7-77b--5-55b~~-|
Ab|-5-55b------------------------5-55b------------------5-55b-----------------|
Eb|---------------------------------------------------------------------------|

solo 1 (Slash plays solo and Izzy plays verse riff)

eb|-----------------------------------------------------------------------------------15b--------
Bb|---------------15b--------------------17b-15b-13-12b-15b~--13b12b-13b12b-------12-13---13-12b-
Gb|-12-14b-12b-14b----14b-1212b~~------12---------------------------------14b~~~-----------------
Db|-------------------------------9/14-----------------------------------------------------------
Ab|----------------------------------------------------------------------------------------------
Eb|----------------------------------------------------------------------------------------------

eb|------------17b~~-17-15b~~~-20b19b20b-22b-20b19b-20b19b20b-------------------------|
Bb|-12-13b-15b-------------------------------------------------17b~~-17-15b-----------|
Gb|------------------------------------------------------------------------14b-12b~~~-|
Db|-----------------------------------------------------------------------------------|
Ab|-----------------------------------------------------------------------------------|
Eb|-----------------------------------------------------------------------------------|

then play the verse again
then play chorus again

solo 2 (Slash plays solo and Izzy plays chorus riff underneath)

eb|-----------------------------------------------------
Bb|--19b~~~~~~~--19---19bp17-19-1717----20-17--20-17b---
Gb|-----------------------------------------------------
Db|-----------------------------------------------------
Ab|-----------------------------------------------------
Eb|-----------------------------------------------------

eb|-------------------------------------16---18b-18p16-
Bb|-1517--1517--------1517------------13--16-----------
Gb|--------------------------------/13-----------------
Db|-----17----19b1719----19b19b17----------------------
Ab|----------------------------------------------------
Eb|----------------------------------------------------

eb|-1618p161620192022b--20192022b--20192022b-22b22b-------
Bb|------------------------------------------------2022b--
Gb|-------------------------------------------------------
Db|-------------------------------------------------------
Ab|-------------------------------------------------------
Eb|-------------------------------------------------------

eb|-----------------------------------------------------
Bb|--2022b-202222b-202220--20~~---2019----19b-17191717--
Gb|-----------------------------------------------------
Db|-----------------------------------------------------
Ab|-----------------------------------------------------
Eb|-----------------------------------------------------

eb|----------------------------------------------------------|
Bb|-2017--17~~15~~12~~~~~~-----------------------------------|
Gb|------------------------12~--11~---11b-9~---7---5/4-------|
Db|---------------------------------------------------5~~~~--|
Ab|----------------------------------------------------------|
Eb|----------------------------------------------------------|

bridge (the bit with the phone in) (Slash and Izzy) 
    G5   D5   C5
eb|---------------|
Bb|---------------|
Gb|------7-7--5-5-| (dont know how many times this is played
Db|-5-5--7-7--5-5-|  but its easy enough to get)
Ab|-5-5--5-5--3-3-|
Eb|-3-3-----------|

end of bridge (Slash)
   G5           C5
eb|---------------------|
Bb|---------------------|
Gb|--------<<<<<5555555-| x1
Db|-5/0----<<<<<5555555-|
Ab|-5/0----<<<<<3333333-|
Eb|-3/0-----------------|

then play the chorus again

outro (Slash and Izzy) (played straight after the last chorus)
   C5           G5      C5
eb|-----------------------|
Bb|-----------------------|
Gb|5-5-5-5-5-5----------5-|
Db|5-5-5-5-5-5--5~~~~~~-5-|
Ab|3-3-3-3-3-3--5~~~~~~-3-|
Eb|-------------3~~~~~~---|

thats it!