Leaf Spring Bushings & a Vibration

[OleMossyHorns]

Couple of questions I hope you folks can help me with.

86 K10, the owner I just bought it from had installed 4" lift front only using aftermarket springs. I am restoring this back to original. He still had the original springs so I want to reinstall them. While they are on the table I decided to install new bushings. Now the problem, I have been to at least a half dozen auto parts stores and I cannot find the bushings and little tube for the rear shackles on the front springs, ANY HELP OR IDEAS WHERE TO LOOK?

Second question, I put new tires on the original rally wheels. I didn't really notice it before, not saying it wasn't there, but now I have a pretty good vibration or shake between 40 & 50 mph, down shifted to a lower gear and its still there. I don't feel it through the steering wheel. ANY HELP or IDEAS?

Thanks folks, I am new to this board. Will try to include some pics soon.