Evo's are good I had one before my esc cossie, there is nothing wrong with the gear boxes or the diffs, never heard of a box or diff going and I know hundreds of evo owners.
AYC rear diffs YES but not front diffs, the bolts sheer regularly that mount the diff but thats easy enough fixed.
Very fast, very capable car, with good brakes, latest technology compared to the escort cossie, recommend.
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www.lancer-evo.net