Here is the message from the horses' mouth:
"The AM its added about 40 lbs over the 3 link with floater. I don't know about leaf vs 3 link, but the 3 link has less Unsprung weight. You can feel it even driving in a parking lot! Somewhere I have the 3 link weight. I think the leaf springs are 45 lbs each, most of it Unsprung."

So long and short, 40 lbs of sprung weight all in the rear. Not a bad bit and I'm thinking with the new Alloy housings hitting the market, maybe a few more lbs could be lost.

I don't really think the difference between GM/Ford Mopar makes a whole bit of difference, as the weight differences shouldn't be too more varied that the half dozen spring and rear options we all have. Everyone is going to be a bit different from 8.25's, 8.75's and Dana's. Not to mention 3 leaf packs, 7 leaf packs, etc.