Upper and Lower Shafts

[hot!rod]

I am about to do the 4/6 drop. I will be changing the bearings, seals, ball joints, upper bushings, etc. BUT should I change the upper and lower shafts? I've never changed them and not real sure why I should but I'm sure someone else knows. They don't look like they will be much fun. I get pretty decent prices at the local parts store, but not gonna change it unless it's needed. Anybody know anything ahead of time that they need to tell/warn me? I know the typical ball joint routine. I kinda dread the bushings though. I've never had a set of those go smoothly. Oh yeah, I will be changing the idler arm, pitman arm, rod ends, etc. as well.

Any input?
Thanx,
Brad