Ah yes Landy rust, the thing that keeps me awake at night and cussing in the workshop :)
I have rebuilt a good many LR's now and as many posters have said, if its steel, it will rot.
There is no real wonder cure for it and my approach is not the cheapest and is done to keep the vehicle on the road for as long as possible.
Chassis, shot blasted, then hot dipped galvanised
Bulk head, replaced very time. Then either chemically stripped or blasted (carefully) and then hot dipped galvanised. I choose not to repair bulkheads anymore becuase of the time involved. The repair pieces and panel beater labour costs me more than buying new genuine TD5 bulkheads.
Doors, its an art. With a great deal of care and keeping your cool it is possible to get the bottom of the door skin away from the door frame. Cut out offending rotted section and weld in new piece. You can buy replacement door frame sections. If money is not an issue, buy new doors!
Body to Chassis area has a piece of inner tube bonded to the chassis and it helps a lot.
Althought not a rust problem, I also put rubber rings on top of the springs. It helps reduce road noise.
Fuel tank always gets stripped and painted with Ziga paint. Its tought paint thats nearly all Zinc and has been used in the North Sea oil platforms for over 30 years. Sometimes I will pain bulkheads with this stuff if Galvanising is not possible within the time frame given.
Under the floor is usually best repaired by cutting it out and replacing.
If you go with a major bulkhead repair or replacement, do the wise thing and fit an uprated wiring loom.
Emerald

