1st gen drive shaft issues w/ lift?

I have a 2001 DCSB with auto trans. Last week I added longer shackles to my DAKARS which put me about 3.25" of rear lift. A week later I started to feel a weird sound coming from underneath the truck. It's kinda like a muffled rotating thud/ thump. Kinda like what an out of round tire would sound like. It's not constant though, only happens sometimes. Usually when I take my foot off the gas. Ball joints, and bearings sound and feel strong. Anyone else have issues with driveline after lifting any amount?

Since I'm at 3.25" on the rear end should I have added a Carrier bearing drop/ spacer?

I've researched this but only found second gens with this issue after lifting.

Here's a pic of where my drive shaft meets the transmission. It's not flush, so is this an issue?

 

You should be looking at the rear pinion angle. The rear flange is the one that changes, especially with shackles, I had daystar shackles with stock leaves and they vibrated like crazy. Here's this http://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml