On my 91 standard cab the rear shocks got snapped, by getting winched kind of sideways when I got it super f-n stuck on a spooky icy hill...(long story) So I drove it for a couple weeks til I got the funds to fix it, and It was way sketchy to have no shocks. it was like the rear end was on a pogo stick. really bouncy on speed bumps and rollers at highway speed. (NM pavement is not exactly smooth) the shocks resist upward/ downward energy as stated above as well as provide torsional stability (resist body roll?)
So, umm save up for 5100s ? ....like someone told me... they spent millions of of dollars on engineering these trucks... do you really want to go change something (I.E. like adding a spacer lift for looks) ....thats my .02
BTW, I have been working on it myself... got 5100s and LR UCAs, which arent installed yet... still saving for dakar leafs, or maybe I shoulda just done the AAL too. $80 vs. $400...
anyway good luck mang