Rough ride / driveline vibration / crappy shocks in rear?

Well I lifted my truck about a year ago.. Never did replace the rear shocks yet. Rode fine through town which is all I really ever drove it. Or when I went on the highway I had my boat hooked up which probably masked it...

But.. now I am driving it more empty and on the highway and it shakes like hell. Thought it was the drive line but I have put multiple different amounts of drop on the CB without much real change.

Road surface seems to make a difference... sometimes I can go 70 and smooth, others it shakes pretty harsh.

Could it just be the rear shocks? I have some 5100's on order and should have them soon. Hopefully that helps it. I can see my bed flexing back and forth from the cab. I have a canopy on and its just plain harsh ride. Feels like I have a flat tire or something back there. Alignment did nothing.

Shakes over 60 mph. But like I said, sometimes doesnt shake at all. I have the CB dropped about an inch at the moment. No axle shims.

5100's at 2.5" in front. 2" AAL in rear. 170k mikes on the stock rear shocks.

Seems the more weight I have in it or tow, does not shake much.

 

Well, the 5100s in the rear made a world of a difference... Can of course feel the road, but it feels like a truck now and not a rythmic bouncing. Very happy.