Have the front suspension and steering components inspected, and check the tires for belt separation, balance, and alignment. Shake that increases with speed can come from a separating tire or worn front-end parts and can be dangerous to drive with.
The owner reported steering-wheel and interior shake that worsens as speed increases. The listing shows a 1988 GMC with an unknown model, while the post mentions an Oldsmobile 88, 1996, and 137,000 miles. Experts advised checking front-end suspension and steering parts, tire condition for possible belt separation, tire balance, and alignment.
