Consulting the google... it sounds like some of the people have complained about Tatton's shafts not being balanced, any issues lately of this happening? Most of the reviews appear to be from 2010 or so.
My current rear shaft probably has 5000 miles on it or so and the slip yoke is very worn out and has play and it vibrates like crazy above 30mph. It was greased heavily when new but I never greased it a second time. 5000 miles in my mind is not a lot. It has two Moab trips, a handful of short wheeling trips like 5-mile and a bunch of street miles. Needless to say I'm very unhappy but the shaft was built four years ago so even though there is very little use on it I can't go back to the shop (plus it's in Vegas).