TD5 all the way, just buy a diagnostic machine then u can fix just as easily as any other. Treat it well and enjoy 250,000 out of it without a cough or a splutter. The question was engine here, and it's without a doubt the best.
If u think about it, LR spend multi millions on research and...
I bought an 03 disco 2 last month. XS spec, leather and suede, mint bodywork, no noises, mint 18" alloys 110k miles, full roof rack and ladder, 7 seat... £5000
Just to give you an idea!
(mines an 03 XS with TC but no CDL),
CDL and axle lockers do not in any way prevent wheel spin. You must understand this to grasp the principle. A wheel which has no traction cannot be forced to have traction. A diff lock (centre or axle), just ensures that the two things it's joining together...
If you can see it leaking, you're in luck...kind of. If you can't see any wet or leaks, it's most probs HGF.
Get it sorted ASAP! :) thats my two-pence-worth!
Have fun!!