While I don't have any documentation for a 97 I might have some for a 95? Anyway, the best way to find out if your D90 is still under any type of warranty, i.e. corrosion, exhuast, is to ask a LR dealer. This is because it depends on when your D90 took delivery to the dealership in which it was orginally sold from. If you've passed this date by any term of the warranty then you're probably out of luck.
I wanted to make a claim on my D90 so I had Land Rover of Portland look up the delivery date and confirm that, at that time, I still was under my corrosion warranty. The Land Rover representative passed through Portland, inspected my D90, and approved the work. I'd also ask Martin Podagorski, he'd probably know a little bit more about it since he works at LR Fort Lauderdale. But you better hurry! Just remember, you can make a claim on the D90 all the way up until the day the warranty expires. They won't like it, but in most cases I believe they're obligated. Hope this helps out.