If the car is a two seater, very easy to check for the axle hitting the woodwork. Lift the floor behind the seats and look! You'll see rough wood on the rear panel the propshaft goes through.
Quite common for the woodwork the propshaft tunnel screws into to be a bit oversized. Very early on in the ownership of Woodstock, I had this, and it was worse if there was a passenger. A bit of filing of the wood cured nearly all of it, but I'd still recommend a panhard rod as a car so equipped is much nicer to drive.
