transman, i don't know about the crankshaft, but watching a driveshaft spin at 1000rpm is visually terrifying to those who seldom watch something like that, and believe it or not, that is slow !
big truck shafts are spun slow because with their big tires and many other various vibrations present [at various frequencies] the shafts themselves spin at a slower rpm, plus are [usually] shorter than a car shaft and much, much larger in diameter [which absorbs vibrations] , so the multitude of vibrations and their frequencies tend to cancel each other out [somewhat].
car shafts need to be balanced at a faster speed, some as high as 5-6000rpm, due to overdrives, deep rear gears, and smaller diameter tires [i think denny's spins them as fast as 10k rpm . i saw their add in "nitro madness" magazine].
just because truck shaft places have been there for years, and have a great reputation, doesn't mean they have the newest high speed balancing equipment, simply because they do mostly truck shafts which don't require it.