"Tim, are you sure that there isn't a lock retainer hiding under the weatherstrip on your rear door like there is on the right side door? It doesn't make sense that the only access would be from a panel that far from the point needing access."
Well, Duh, Kevin . . .
It was a long time ago when I glued-on on new rear door weather-strip that hides that retainer-clip.
I owe you a few beers and/or a few shots of a good Single Malt Scotch Whisky.
I'll report back - when I succeed.
Thank You very much