I was wonderring if anyone has installed a toyota locking rear diff. on a 3rd gen 4runner that did not have it? I know on the new FJC alot of the hardware for the off-road options are installed even if not ordered and it is just a matter of getting the wiring harness and switch to activate them (learned this from a friend that has one). Is this true for the RR diff lock? (keeping fingers crossed). If not, how hard is it and cost?