What's wrong with using a sheathed cable and a simple lever on the tranny tunnel?
As per Mercedes G Wagon, good thought Frank, it would remove the electric actuation but I would like to keep the warning lights on the dash, so something would need rigging up. And this brings me to my earlier comment, they work real good as stock so I cannot justify the time and development but, having said that, if some produces a decent kit it may make a great replacement over the cost of a new OE unit.
regards
Dave