Steering wheel shaking could normally be put down to wheel balancing but when you talk about this growling it may be that you have a knackered wheel bearing/hub which can get to be quite noisy at motorway speeds. Sorry I misunderstood your earlier post when you said the thudding from rear was rythmic and varied with road speed. If you can it would be wortnwhile getting the rear end off the ground and turn wheels by hand to check for source of knocking around rear diff and prop shaft. Could also be worth having a good look at tyres for any bulges or defects. Your dry stick noise may just be the ACE. The system has a pressure control valve in the control block which controls pressure in the system. It can noticeably "sneeze" for want of a better word at times where the ace isnt having to workmuch, where no corners such as motorways. Its simply reducing the system pressure. Try leaving idling for some time and see if it happens. Control block is mounted on chassis below drivers seat