Check to see that the ball joints are all lubed......that the emergency brake cable is secure....that the shock bolts are tight ....that the header bolts are tight (after heat cycle)....that the transmission bolts are tight...that the brakes are up to snuff on a hard stop....if the
oil temp was over 110 C if the cooler is hooked up....that the pins are torqued to 80 lbs and are not split.. Did you have the dreaded 65mph shake ???