knocking noise while drive

[iwillnc]

Does it come about during High RPM?

Or over 50 mph it's constant?


I have a rattle in my passenger floorboard that sometimes sounds always above 4500 RPM.


If nothing else you can put the truck into neutral with the park brake engaged and try to shake the shafts.

In which direction does it sounds like it's coming from?
And your sure it's a knocking and not a clicking?