Here are the rear door lock components:
LS LT Focus Rear Door Locks.JPG
As for part number N808594-S100, that was used here in the 2000-2002 Tickford Converted Mustang that held the handbrake bracket to the floor. Obsolete from Ford, I believe its a 6.4 blind rivet. So go to any fastener place and they should be able to help as per example below.
https://www.ebay.com.au/itm/Qty-25-D...UAAOSwkXdd8wgo