I have a 1996 GMC Sierra 3500 Vortec 454, I have spend literally thousands of dollars of the last few years trying to have this problem fixed. When I am driving on the highway and hit about 100kph the truck starts to vibrate and shake. If I have a drink in the holder the truck shakes so bad it starts to spill. I have had almost everything changed in the last 2 years and it still doesn't run properly. You name it, I have it replaced or fixed, I have had my truck to about 5 different mechanics and they say nothing shows up on the scan. With almost everything replaced on this truck I am getting very frustrated. The shake starts at about 100kph and stops when you get to about 100kph. Has anybody else had this problem?

Welcome to the forum. Have you checked the u-joints? The u-joints will cause vibrations at certain speeds.

Pretty non specific question, how does this shake manifest itself, in the floor, in the st wheel, as an engine misfire, wheel/tire vibration? What was done so we don't recommend the same repairs.

Pretty non specific question, how does this shake manifest itself, in the floor, in the st wheel, as an engine misfire, wheel/tire vibration? What was done so we don't recommend the same repairs.

The dash shakes quite hard, I have repaired intake gasket, throttle body wiring harness, new plugs, new ehaust, all new sensors, fuel pump.

Have the tires been check for being out of round, bent wheel, bad dr shaft u joints? Bent driveshaft or kinked? You say "everthing" has been replaced but from your description nothing pertains to the symptoms, has a mechanic driven this and suggested what the problem may be?