Heres the truck info:
2002 Ranger Supercab 4dr 4.0 SOHC, 5spd manual, 104,000 miles.
I just put a brand new OE ford clutch kit & slave cyl. in the truck. I now have a vibration at anything faster than 55mph. Wasn't there before I did the clutch. I used the alignment tool that came with the kit and everything went together very slick...in fact was the easiest clutch I have ever done.
I originally thought maybe the driveshaft had to be oriented a certain way and I should have marked the flanges where the driveshaft mounts both at the rear end and transfer case...but if these driveshafts balanced out of the truck then it shouldn't make a difference which bolt holes are used in the shaft vs. the rear end & tranny.
I then thought maybe the flywheel in the engine was the source as I did not get a new one or get it re-surfaced, I just took a scotch brite pad and took the glaze off it. But....when going 65-70 MPH and you take it out of gear and let it idle, or put it in a different gear it doesn't change anything so I don't think the flywheel is the source.