Grinding/Rubbing Noise from front end when I let off the gas

[60stepside]

Long story short. Left wheel bearings went out, so I relaced them with the bearings and hubs from a 68.

Now I am getting a grinding/rubbing type sound from both wheels (not at the same time) when only if I hit a bump/pothole or if I gunn it and then let off the gas and the front drops back down. If I just cruise and avoid potholes or bumps no noise. I was thinking maybe its the drums rubbing on the backing plate, so I took off the wheels and checked them for any kind of freeplay (none) I also turned the the tire really fast it made no noise. Maybe it only rubbs when the front end is under load??? A little more info, the truck was lowered before I bought it. It looks like the spring was removed and a shock was added (no expert here) could maybe the shock has died and now its causing some weird problems?

Any help would be awesome!