The actual chords for Dear Brother are, in my opinion, Fm, Eb, Cm, Bb.  But because Eb 
and Cm are such difficult chords to play, I recommend:

Tune your guitar to Eb (1/2 step down)

I will write the chord names as if you were playing on std E tuning (IE Fm becomes Em)

Em (022000@1)           DReminiscing (xx0232@1)on our indestructible days
BmThe (x24432@1)party never seemed to end
A (x02220@1)                         Em... D... Bm... A...
We donkey punched the night away

Em (022000@1)                 D(Sin (xx0232@1)after sin) 25/7 some risky business, my friend
Bm (x24432@1)                      AFortunes (x02220@1)seem to favor us 'round every dark and twisted bend

Em (2nd time Bm)        D (2nd time A)
You can't cheat death, can't outrun the grim reaper
(repeat)

Em (022000@1)                         DThis (xx0232@1)glass I raise is heavy, heavy as my heart this day
Bm (x24432@1)                              AThe (x02220@1)reaper slipped right past us, bastard stole your breath away

(Em/drum-solo)

Em (022000@1)                      DWe (xx0232@1)raise a heavy glass to you in our indestructible days
Bm (x24432@1)                     AMay (x02220@1)heavens call to you may stars align and light your way

Em (2nd time Bm)
Farewell, dear friend
D (2nd time A)
Fare thee well, dear brother
(repeat)

Em (022000@1)                      DA (xx0232@1)sad and joyful toast to you, heavy is my heart this day
Bm (x24432@1)                           AOnce (x02220@1)more into the breach, dear friend, donkey punch the night away