I had a look through posts for vibrations but couldn't find something similar enough to what I am experiencing; at a speed just under 30mph there is a vibration in what seems like the whole vehicle. At maybe 35/37mph it goes away and becomes noticeable again at 65/70mph, but at that speed, somewhat less noticeable. Any ideas what could be causing it? I got the front wheels balanced, but that didn't help.
Thanks in advance!

 

Sounds like a front driveshaft to me, in my limited Rover experience. The way I knew it was mine is like you said, at low speed it shook a lot, but around 70 I felt it again just at a higher "frequency" so I knew it was somewhere in the driveline.

 

front drive shaft x2

 

Better do the drive shaft before it breaks free and smacks the transmission right out of the truck!

 

See those hairline cracks? Imagine what the fractured end will do with sharp and jagged end, turned at speed by the velocity of the vehicle and front differential. Warning can be less than an instant. Presented as an example - your exact conditions may vary.

 

thank you all; it was the front shaft. Now the wallet painful part, but better than the alternative as you all point out.