Seems I have found my mystery 60mph vibration,i'd checked tyre balance,drivetrain condition and pinion angles etc,i'd convinced myself it was from this.
Long story short,my alternator recently took a dump the other day (bearings).

On removing the offending item I found a crack in the mounting boss,which it seems had caused the bearing failure in the first place.
On installing the new Bosch alternator and subsequent road test,the vibration has disappeared!
My local FLAPS did me a storming deal on a rebuilt unit. £60 all in (about $90USD)
Great for a model specific item,even more so being for a 'Yank' here in the UK.

I love it when things like this happen,now onto the next 5500 miles!


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.