drive shaft tremble

so here begins my tale of woe.........
after being a terrible owner and neglecting my landy for a little while i eventually found a dry day to get underneath and try to get the bottom of a mysterious scraping noise that appeared to be coming from the drive shaft. when i found that the 4 bolts that attach the universal joint onto the front diff were loose i thought i had nailed it.
pleased as punch i dutifully tightened them up and took it for a run to admire my handywork.

the vehicle runs like a dream......until i hit about 40mph. then the whole drive shaft vibrates and trembles, as soon as i depress the clutch it stops


any ideas guys and gals?

thanks in advance

Remove the whole front prop shaft engage diff lock and try again, whilst the prop is off check the uj's, then do the same on the back

take the whole front propshaft off, engage difflock and then get it up to 40?

Grease in grease nipples first

Check for play in prop spline joint and check for side to side movement in diff output.

thanks i will have a go monday and inevitably end up asking more questions