my father has a 97 formula 583 with the base hydraulic shocks and no acm. the rear shock i shot and he wanted to replace it with a HPG rebuildable shock, but we are not sure how to get one that is gonna be valved right for his sled. will a 97 mxz shock fit this sled? if it will, will it work with the springs on his sled? if he buys an aftermarket shock the right length how do we kno what the valving will be like? thanks for any tips!