[ImperialCrown]

Welcome to Allpar. Inner axle driveshaft joints can cause a vibration/shake under load. Outer joint vibration happens mostly under load while the wheels are turned. Diagnosis can be difficult with the rubber joint boots intact, but the right, inner CV joint grease can get cooked after sitting a few years next to the hot catalytic converter.
Any looseness or wear in steering or suspension components can make the shake worse.