From the way I understand it, if one were ordering shocks from LMC, (a handy reference at times if nothing else)

, looks like there isn't any difference.
http://www.lmctruck.com/icatalog/cc/full.aspx?Page=51
Agreeing that the shocks are just there more for ride and stability while the springs are what handles any real weight.
I do know before I replaced the shocks on the C-30 the rear was hopping all over the place with the slightest bump. Now it doesn't. As I understand it, that is why Chevy went with the staggered shocks in the rear to get control of "wheel hopping" in the back.
New front shocks definitely added to a more comfortable cab ride too. Worth the expense if needed. Just be prepared, as I wasn't, when taking them off, that chances are some idiot may have used an impact gun when installing the old ones!
Took a breaker bar to get the front ones removed.
Mark
__________________
1985 Chevy C-30 Hydraulic Dump Bed
2001 Saturn SC2 (go to work car)
2010 PT Cruiser (wife's car)
"Reality is just a hallucination brought on by lack of alcohol."