Having ruled out all other causes of vibration at 50+mph( wheels,diff mounts,gbox mounts, driveshafts etc), I bought a new prop for my OD Vit last year from Bailey Morris. Cost ยฃ300.00.๐ Looked like a nice job, but when fitted I noticed a small amount of play in the sIiding joint and still had vibration! So back it went for a rebalance. They also replaced the sliding jt . Fitted prop again, still had vibration! ๐กI ended up taking the car to Vibration Free Services in Bicester. They put it on the ramp and ran her up. After a lot of testing,they measured 28 microns out of balance at the diff end, IIRC. They did'nt want to disturb the welded weight already on the prop, so eventually fitted 2 jubilee clips and that figure came down to 3 microns. This process took about 3 hours of test, adjust weight posn and orientation,measure again + a couple of road tests. Car now drives fine. I've never really understood why some Vits seemingly don't suffer from prop vibration at all, and others do. Are convertibles more prone? Are Mk2's ( mine) more prone? Does the extra weight of roto wishbone, and cast v links increase the likelyhood?