[saintjoelarry]

Though this is not likely the case for a Model A, since others are mentioning other vehicles they've had with the problem, here's one for you. Many years ago we had a 1974 Dodge B100 van. It would get the death wable like nobody's business. Shook the entire van until you brought it down to a near stop. Replaced every stearing linkage on the thing, then finally decided to tear into the stearing box. While unbolting the box, found a crack in the frame right around the the mounting bolts. Took the stearing box out, welded up the frame and never had the problem again.