Got new rear KYB struts & rear upper strut mounts from 1A Auto. Went to assemble everything & the rear upper strut mount bushing wouldn't slide over the strut shaft. Thought something might be wrong with the upper strut mounts & went to Advanced Auto Zone to get a set from a different manufactuerer. Same issue. Figured maybe KYB struts are made with a slightly larger shaft diameter. So then I got AC Delco OE struts. Can't go wrong with factory, right? Same issue! So I guess my question is: can you use rear upper strut mounts without using the little metal bushing? 1999 Monte Carlo Z34.