hello all just a quick question i was hoping someone could clear up

i have a s1 one and it needs a new gearbox its not completly gone yet but its hanging in there for dear life

i was hoping to get a box with a longer final drive some one told me the fiesta rs turbo has a longer final drive is this true and if so will it go stright on ?
as im fed up with doing 80 mph at 4000 rpm (or so) and with the cossie management on it its drinking juice no end on long runs

also i have heard that a diesel box from a mark 3 will go on

please help as i aint got a clue

cheers peeps

justin