Land Rover Repair: 2003 range rover, stering wheel, speed range


Question
"I was on the highway yesterday and while in traffic, felt an unusual shaking from front to back.My truck has 60,000 miles on it but I recently got a new tranny, spark plugs,and changed all oils, would you know what the problem might be? "


Answer
And in your oppinion where from the shaking comes? From the engine? From under the vehicle? Or the whole body was shaked? Or just the stering wheel?
And mainly in one speed range? For example just shaking at 70-75 mph, or the shaking was stronger while the speed (or the engine rpm) changed?
What type of engine you have? 4.6 v8?

So please try to tell me more enviroments.