Jan, I suspect that owners simply didn't want to stress the motor mount bolts or the engine mount castings by jacking up the rear of the powertrain enough to clear the steel ZF mount tabs. And they probably didn't want to climb underneath once again to loosen the bolts.
Plus its hard enough to slide that 160-lb lump of metal (the ZF) back onto the bellhousing & into the pilot bearing when its all horizontal; trying to wrestle it in at a 60 degree angle while a foot in the air makes my back ache even thinking about it! And a few rear windows have been broken by Weber velocity stacks while getting creative with powertrain angles. Good luck & let us know how it runs at the end.