Hi all, I'm doing the same thing, infact I've been working on my V8i D90 for years and been collecting parts since I started 10years ago. For a long time now I've had a rectangular block speed transducer and its btacket tht fit down by the gearbox, the sort cable that goes between that and the box and the long one that goes betwwn that and the speedo head. Believe it came off a rangi but was an ebay buy if I remember right.
Now that I'm at the stage of fitting it I've found that even though it fits the speedo drive of mw LT230 (also from a rangrover) it does not drive and turns out wont fit my speedo anyway. On investigation I've found that the cable and also the tranducer have a 2.5mm square drive end yet the gearbox drive and the defender cable I also got have 3mm square drives.
Has anyone else come across this and are the parts spoken about above (The box type transducer is AMR3386) correct?
any help welcome
