The strength of the diff isnt so much the problem, sure you'd probably want to replace it eventually, but its more the diff's ratio needs to match the gearbox that you get with your half cut. not to mention (but this is needed for both options) genuine rad fluid, engine oil, gearbox oil, diff oil, gaskets ($$$) its also worth while doing a service on either motor while its out (oil filter, timing belt, water pump etc)

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MY93 Impreza GX 1.8L, 0hp, 0nm