Sounds like running over rumble strips. Seems to be morenprevelent when Golgotha up hills.
Torque converter shudder is one possibility.
A bad wheel bearing is another possibility.
Whether you are driving to Calvary, or not, I think that a bad Torque Converter Lockup mechanism is the source of the problem.
Personally, I’m on the road to shambala
That rumble has been the lockup torque converter on many vehicles I’ve checked in the past.