Land Rover has used AL for body panels in a number of vehicles. The frames have always been steel. The uni-bodies of the Discoveries and LR3/4 are steel with some AL panels. The D1 and DII had AL quarters. The LR3 has an AL hood and upper tailgate and I thing the radiator support is AL. I don't believe anything structural was made with AL. The DI had some notorious rust problems around the rear skylights. I think there was even a recall for it. I had never seen anything more than just surface rust on the frame on my old DII and it was flooded with salt water (RIP). I think modern painting and galvanizing has more to do with LR's appearing to be rust free than anything that they might do with AL. The all AL Range Rover could be a game changer as far body longevity goes. One small issue with AL, it's much more finicky when it comes to prep for painting.