I have the servicemen's reference book for d315,d4,955 traxcavator and in page 275 they give indication lift the starting engine 2to3 inchs thick this will permit the starter pinion to pass by the idler gear,removed the cover from governor
,engage the cluch pinion this will mesh the teeth on the pinion with the teeth on flywheel gear and make removal of the cluch and pinion possible and dont forget to remove the 2 or 3 bolts from rear inspection cover for twist the cluch housing comming out ,if you could get themanual it should help you and my manual is bad with finger praint and corner eat by mouse in shop.