Renault Espace Driveshaft Problems

Have vibration/wobble at 44 ish mph, and is felt in the seat, not in steering wheel. Have swopped over to a different set of alloys/tyres and problem still there. Garage checked front steering/drives and cant find anything. Others ...

would changeing the stableizer link bars stop the vibration in my frontend/steering

having checked wheel balance,tracking, ball joints etc,would it be the drive shafts or the gear box causeing the front end vibrations

front wheel drive shaft lacks grease. needs servising