Dear H.A.M.B'rs, Drove form Indy to Knoxville, TN for the NSRA South show the first of this month. The drive down was smooth and uneventful. Not so on the return. My coupe (40Ford) developed a pretty bad shake (it was as if I was driving constantly over those warning cuts in the road that you are going onto the shoulder). This shake occurred above 55 and would not dissipate thru 75 or so. I darned not going any faster. It seemed to go away for a bit if I changed lanes. This occurred on I-75 starting in KY and into OH. But when we changed to I-74 in IN. It stopped and I could not make it return until we took some side roads as interstate was getting nuts. Then it reappeared at 40 to 45 and would not stop no matter the speed. Upon arriving at home I noted that the front brakes (GM single piston calipers)appeared to be locking up. After changing out the pads, replacing the calipers and turning rotors I took it for a drive, no issues. The next day I took it to the interstate shake was back not as bad but back, side roads are fine not at 65 plus. Took it to my friends shop who re-balanced the tires (new Diamond Back radial) They came out fine. Put it on the lift, ball joints, steering rack, u joints all seem to have little to no play. Put is back on the interstate. Shake time! The steering system is : Early 70's GM van going into an upper u joint, welded to an approx 16 " shaft going into another u joint which fits onto the the Mustang ll spline. So this afternoon I am under the beast and grab the steering shaft. I have a bit of play maybe 1/32 of an inch in the u joint closest to the GM (circa 70's van) column. The column shaft also has a small amount of play. Central question how much play is too much and why would this shake come on all of a sudden. I can not find anything broken or loose. Looking forward to your input. I am tried of this tune!