WARNING: This page is about a different car, the 2002 Mazda MX-5 Miata and 2001 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.
Drill holes around the differential mount.
Fig 1: Drilling Holes Around Differential Mount
Courtesy of MAZDA MOTORS CORP.
Hit the edge of the differential mount to remove it.
Fig 2: Hitting Edge Of Differential Mount To Remove It