They went from the rotated joints to a Double Cardan at the T-case and a single cardan at the diff. This change was made with the DII. At the dealer we were often retrofitting on D1's and D90's.
Hmmm, I've been around the LR world in the US since about 1996, owned a manual D1 and still own my '95 NAS D90. I don't recall ever hearing of front driveshaft issues with either vehicle, nor dealers replacing with double cardan shafts on D1's, Defenders or RR Classics. So this one is news to me.
I do remember Disco II's having issues with the DC front shafts breaking, and taking transmissions with them quite frequently though. Pretty sure that was determined to be an issue with not being able to grease the joints, and they would fail as a result. Don't recall if there was a formal recall on them though.
My Disco ('96) had about 3" of lift, and I replaced the rear shafts 'rotoflex' (rubber donut) with a standard UJ, as they would rip themselves apart pretty quickly with any lift over 2", never had any issues with the front driveshaft, but had to put a new R380 gearbox and LT230 TC in it due to spline wear Issues.
Either Way, very disappointing the number of issues with the Grenadier platform. It may as well have been produced by Land Rover, and between the drive shaft issues, and the power steering pumps that make them sound like 30 year old crap, I've not been able to 'convince' myself to take the plunge, particularly at the asking prices for these things.
I also know I wouldn't be able to leave it stock, which seems to pretty much nullify any type of warranty response, so..