GORDON GT SERIES 11

hi all i put a gearbox into my 99 uk spec impreza which had a code ty754vn1aa the gearbox the box i put in was out of a 04 wrx which had a code ty754vn5aa.i have a few problems since i done the job there is a small oil leak from the inner shafts i am not sure whether its the oil seal ring on the end of the shaft or the actual rubber seal in the box itself an help would be great cheers lads