Just weld it. If you had a ke30 all you would need to do is drain the oil and take the plate of the back of the diff and you can weld it while its still in the housing. With a ke55 you will need to pull the center out to weld it (i think??? never pulled one apart).
Then get a window washer setup, fill it with diesel, position a jet each side of your car so it sprays onto the back tires and do sum spinny's.