Noises are obviously hard to diagnose on the internet,unless you post a video with sound.
I assume the noise is emanating from somewhere other than the engine bay?
A worn out UJ can cause knocking/clunking,are you aware of any vibration related to the noise?


1950 Chevy Advance Design 3100 in Scotland
In the Stovebolt Gallery
More pix on Flickr.
I've definately got this truck thing in my blood ... my DNA sequence has torque settings
"Of all the small nations of this earth,perhaps only the ancient Greeks surpass the Scots in their contribution to mankind" Winston Churchill.