Dude looks cool but do you have traction bars or anything under it? Also could be your pinion angle. Did you change rear ends/ Is your driveshaft to short or long? I have a 55 sedan tubbed w/ 18.5 Mickey's and 15x15 dragstars and it does shake a little at certain speeds but when I'm smoken them it's soft as silk. I'll look and see how they are bal. tomorrow and let you know. I did go to a shop that does my 35's on my truck. Don't know if they have any special equipment. Good luck