Truck vibrated between 45 mph to 70 mph when gradually accelerating.

There is many reason this could be happening. A little more info is needed in order to even try to diagnose the problems without being able to lay hands on the vehicle. Like does the whole truck vibrate, are there any new noises when starting the truck and reaching 45 mph, does the steering wheel shake from side to side like it is trying to turn its self, can you feel the vibration in the brake pedal when applying the brakes, also what year, make, and model is the truck.