tuning doesnt sound right. i think its just drop d.

I think the riff sounds better like this.
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--------------------------------------------------------------8-------------------8--|
--------------------------------------------------------------7-------------------7--|
-0--3--5--5b--5b--5--5--3--3h5--5--3--5\3/5--5--6-----5\3/5--5--6--|
--------------------------------------------------------------------------------------|
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If not that, then this
--------------------------------------------------------------8-------------------8--|
--------------------------------------------------------------7-------------------7--|
-0--3--5--5b--5b--5--5--3--3h5--5--3--5\3/5--5--6-----5\3/5--5--6--|
--------------------------------------------------------------------------------------|
--------------------------------------------------------------------------------------|
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Maybe needs a little tinkering.