the diff is a bolt in on the 182
and on the 172 its some sort of circlip ?
the 182 boxs are stronger apparently.
i did feel a difference between the two when driving(you can say its bulls**t all you like but i did feel a difference between ph1 172 box and a 182 box)
& the washer blanks are silly prices like 80 quid for a piece of plastic?