After my wife has been driving this Land Rover for a while, We :-) have decided to sound proof it.
Taking the trim panels off the sides and roof revealed no sound deadening at all, so a blank canvas.
The roof was degreased and fitted with Dynamat sound deadening sheets, then covered over with closed cell 5mm adhesive foam.
The seat boxes, bonnet (hood) and the three doors also got the same treatment. whilst we had the trim off the doors they were rustproofed using Dinitrol 3125 Cavity Wax.
This has made a huge difference to the sound levels inside the Land Rover, making it pleasant for long journeys.