Turboman
Mab An Gov
I had a 2 year old mk1 escort in the Mid 1970's. The floor didn't rust but the edge of the boot lid and bonnet did, also the top suspension mounts. Volvo led the way in the 70's by galvanising their vehicle body's. I know this sounds mad but I often wonder if the products owners use in an attempt to prevent corrosion actually promote it. I attended the Newbury classic car show yesterday. There was many fantastic cars form days gone by, all in fantastic condition, including many fords from the 70's and a few old vauxalls. Having talked to a few of the proud owners, there was one thing in common, none of the cars saw any use except attending car shows and only then if it was sunny. So that is the answer, lock your landy in a nice warm garage and never drive it again.
Col
Using big plastic wheel arch liners to protect the steel underbody was also a huge step forward in corrosion protection. For some reason, Defenders never made this great leap forward.
Odd drive on a sunny day might be OK. Or else go through it and paint the chassis properly, and spray Dinitrol or similar inside, like the factory should have done originally.