intro/verse
G-----------------------------------------------------------------|
D-----------------------------------------------------------------|
A-----------------------------------------------------------------|
E-5--5---5--5---0-0--0-0------------------------------------------|
repeat until chorus (really thumping bass part, new timing)

alternate intro
G-----------------------------------------------------------------|
D-----------------------------------------------------------------|
A---------------7-7--7-7------------------------------------------|
E-5--5---5--5-----------------------------------------------------|

for the E's (0s and 7s) in the two versions, you can try E (7 on A) and E (0 on E) 
as a chord
chorus
G-----------------------------------------------------------------|
D-----------------------------------------------------------------|
A--------------------------------------------------x-4------------|
E-5-5-5-5-0-0-0-0-------------------------------------------------|
play as quarter notes

post verse
G--------------------------------------------------------------------|
D--------------------------------------------------------------------|
A-------------------7------------------------------------------------|
E-5--5---5--5---0-0---0-0----5--5---5--5---0-0--0-0------------------|

post verse modified
G--------------------------------------------------------------------|
D--------------------------------------------x-2---------------------|
A-------------------7-----7------------------------------------------|
E-5--5---5--5---0-0---0-0--------------------------------------------|

chorus
G-----------------------------------------------------------------|
D-----------------------------------------------------------------|
A--------------------------------------------------x-4------------|
E-5-5-5-5-0-0-0-0-------------------------------------------------|
play as quarter notes

you may want to try a subtle E--4/5-- in place of the A's in the chorus

post verse modified
G--------------------------------------------------------------------|
D--------------------------------------------x-2---------------------|
A-------------------7-----7------------------------------------------|
E-5--5---5--5---0-0---0-0--------------------------------------------|

G------------------------------------------------------------------------|
D------------------------------------------------------------------------|
A---------------------------------------------7----7---------------------|
E-5-(4)-5---5--5---0-0---0-0----5--5---5-(4)-5---0-0--0-0----------------|
repeat until end

notes in parenthesis are notes you can mess around with (I'm not sure if they're there)

We need more Modest Mouse bass tabs yo