I had similar issues on a 2000 Discovery II, 205K miles...mine were mostly related to the auxiliary circuit...wipers, radio, rear view compass intermittently turning off, blowing fuses, and figured out what my issue was...

After repeatedly replacing a fusible link that kept blowing, replacing/swapping relays, checking grounds, alternator tests, ect, I eventually took out the entire under the hood fuse box , and it turned out that one of the wires coming from a wire pack to a connector that plugged into the bottom of the fuse box was badly burnt out and barely making a connection...I replaced that section of the wire, cleaned all the contacts in the connectors and the male prongs on the underside of the fuse box, and it fixed all of the nagging electrical problems I've had.

Just a suggestion for something to check before all out replacing fuse boxes.