replacement pedals are a dodgy area anyway, with regards the law. im 99% sure whatever pedals you buy will have to drilled into place, as there is concern about the pedals falling off otherwise! the stadard 172 pedals are riveted into place, so youd still have to drill to get the rivets in. one thing you could try if you really had confidence in your work, eould be to use some heavy duty epoxy glue or chemical metal to glue them on, but i wouldnt even consider that!