Jack up the rear end, support on jack stands, stick a small flat screwdriver into the speedodrive and spin the wheels.
i took this approach, as you and bda indicated, and get no response.
i have not lubed the cable, but it seems to rotate freely, and seemed happy just sticking thru the "fascia", until it stopped being happy....
that unit seems to plug into the transmission thru some nylon looking bush- mabe held in by a set bolt in the case(i see only two fasteners that seem involved).
i understand there may be some plastic pieces in that drive?
can it be removed, hole plugged, and used without destroying anything, while i examine the alternatives.........?
except for leaking final drive seals, the transmission seems fine.
richard