i was tying the stumps around rear axle.
possibly bent the axle housing?
I will almost put money on this being the cause.
Unless the engine is shaking while the vehicle is stationary,and revved up,I doubt it is engine.
go find a hill,and with the engine off,let the truck roll up to 30 mph and see if the shake is there.
regards,Rod
PS: towbars are for towin',axles is fo'drivin !