Old Chevy Lover

I had tried some weight, it didn't help much. What I have figured out so far is it isn't a vibration but I think iylt has something to do with suspension. I think any little bump reverberate thru the cab. Even going slow, I can feel the console vibrate 4 or 5 times when I notice a bump. Once I realized that and concentrated more on that instead of a vibration, going down the road it becomes constant from the cracks and so forth in the pavement. That explains why fresh pavement is much better, too. Now I have to figure out why it's happening. The puzzling part is the lowering struts, factory struts, lowering shocks and factory shocks or any combination - same result...

Yea, factory bump stops and brackets are cut off. I think it's more in the rear from the way it feels. I put the factory front struts back on for a few days, didn't change anything at all. I've also tried rear shock extenders and no extenders. Recently bought one of those tiny sports cameras. I'm going to try to mount it in a few different locations to get an idea of what's happening at speed.

Wanted to check with others that may have experienced this. Lowered my truck 3/5 with Mcgauphys adjustable kit (spindles, struts and flip). Truck rides terrible, most noticeable at highway speed but can feel it at any speed. Almost feels like a washboard effect when hitting a bump. A very smooth, freshly paved highway rides good. 2 sets of tires and wheels, driveshaft shortened and balanced, tried pinion shins, different shocks, nothing seems to help. Rode perfect pulling into the shop, immediately noticed the difference leaving. Any ideas?

Anyone know or can check to see how much of the yoke should be outside of the transmission? Should the rear of the transmission be centered on the yoke? Thanks