ok you have an 88 mj. so you want any parts for an 87-96 xj/mj era. now factory for your jeep offered an internal slave set up. now you want this ideally unless you want to upgrade to a easier maintained external slave set up which has an internal fork so that the slave cylinder is easily serviceable and mounted on outside of bellhousing and get at from under the jeep without having to pull tranny to swap out a bad slave. now external bellhousing are different and can be found in the 95+ era xjs. the big difference between the two are the input shafts diameter. one being smaller then the other. the later year ax15s had a almost 3/4" size shaft and will not fit inside the crankshaft hole thats in the engine. a cj7 bushing from 80' would be needed to do so. and or a bronze bushing would be needed to allow you to run the smaller shafted and older ax15 when mated to a later year 4.0 which will have a larger pilot hole in the crank. so that being said if you already have a new engine with 88' specs then you should continue to build off that and look for parts for 87-94 mj/xj internal slave set up. goes to the flywheel as well, need that renix manual era flywheel to be read correctly from a renix cps. then you will most likely want to install a 23 spline 231j tcase with or without sye. i think i got your questions. ask away though I'm here.