[teknorc]

Hmmm... 150 degrees is normal. If the clutch is 250 or higher, then that is a problem, but 150 is close to the lower end of the temp range. It appears your clutch bell is shimmed perfectly - tiny gap between the bell and the flywheel.

How does the truck run? If there is excessive slipping (no punch), check the slipper clutch behind the spur. If the clutch bell were slipping, the temp would be a lot higher (250-300). One other thing to check if there is still audible/noticeable slipping would be the clutch nut. Tighten it down on the flywheel just a tad more, but this is a last resort. Let us know how it goes.