108's and 113's have similar r&r procedure, i believe. There's got to be some info in the archives here. On a phone or would dig up some links.

A younger me (with an enviable amount of free time) commented on 108 installation, "Lifted up the diff a bit with a jack. Opened trunk - loosened 4 bolts going to frame and 1 large bolt (24mm? )going to diff. Jacked up diff a bit further so mount 'pops' up a little bit. Remove bolts, removeout old mount, pop in new mount. Allign new mount and partially screw in bolts. Dropped diff down partially to center/ seat the mount and retorque all bolts."