I haven't tackled this myself yet but read an article and have gathered the pieces. In this case the shop used another pair of inners and used portions of those to get rid of the "hump" in the outers. You only need the top half so I cut them out of a parts car instead of buying new. The article didn't give a whole lot of detail otherwise I'd offer to copy and send it to you. But doing it while you have the quarters off is the way to go. Just make sure you "trial fit" as you go along to make sure the quarter will still clear the tub !!