In a RWD setup its one large sandwich plate that bolts to the block behind the flywheel.
If you can see your flywheel with the gearbox in then I'd say somebody used the FWD sandwich plate which only covers the top half and leaves the lower exposed.
If that is your issue its time to pull your gearbox out and put in the RWD sandwich plate.
I can supply a RWD sandwich plate if you need one.