discovery vibration

hi all just bought a discovery 300tdi 1995 and its great but have noticed at around 50mph i get a vibration when i am accelerating but the funny thing is it dosent happen every time i get to 50mph .ive checked the ujs and all seam to have no play what so ever and it has all been poly bushed not long ago so all good there ive looked at the rubber doe nut on the rear prop and it seams to be fine any ideas would be great its doing my head in thanks

wheel bearing?

hi thanks but would that not be noisy if it was a wheel bearing

tyres ,try swapping them front to back,ujs can sometime sieze giving vibration but no free play,have a really good look at rubber dough nut as can look alright till power appliued

try checking the intake to the airbox that comes off the inner wing.
i had a vibration at 30mph,replaced all the uj's and rubber doughnut,then found the two plastic push in screws had some off the air intake which should be tight against the inner wing.
have not fixed this yet but tied the intake pipe back and the noise changed so i assume this is the problem.
hope this may help.