Need a higher res picture to be sure but it looks more like a Polydrive or even Allen (hex) key head rather than Torx, unless the lobes of the Torx fitting have been worn away...Stupid question, but you have tried Allen keys haven't you?
The link below refers to these as Torx head screws in the description so that part appears to be verified, now you just need the sizehttp://www.latemodelrestoration.com/item/HDW-21812B/1994-04-Mustang-Door-Latch-Screws
Will go to Bunnings tomorrow and buy a kit. STANDBY
Bunnings have a good exchange/refund policy so return them for the right size if they don't fit.s