To a purist the Series 2 was the last "proper" Land Rover, with a wire mesh radiator grille that is removable so it can be placed over your camp fire, and the metal dash (or "no dash"!) full of metal nooks & crannies just right for removing the tops from beer bottles. The tops fall into the footwell where they can be kicked outside when you next open the door..........
It should have a non-synchro first gear, which is actually a good thing as the fully-synchro box in the S3 was weaker. I've no idea what an Iron Duke is, but the only real weak spot in the drivetrain are the rear halfshafts, but they're a doddle to replace anyway.
The bulkhead and chassis rust, the rear crossmember and all the outriggers are the first to go but anything near the engine/transmission is usually ok due to the constant oil-bath. Galvanised replacement chassis are available. Check all oil levels regularly, gearbox, transfer box, both axles.......
Electrics by the Prince of Darkness, but there's very few electrics anyway.........
Overdrives are/were available, or you can change the diffs to raise the gearing. If freewheel hubs are fitted, check the front swivels as the FWH mean that they won't have been lubricated properly.
This is a good UK-based forum:
LREAnd the more dents the better. Have fun!