I can only tell you what I have learned from my own experience. I installed '03 SVT seats into my '05 ST. I learned that if the air bag light is on, none of the SRS works. No air bags, no pre-tensioners. If your '05 ST came with side air bags, (I believe they all did) the SRS module, beneath the center console, must sense '05 side airbags before it will activate the SRS. There is also a seat position sensor on the driver side seat track which is esential to the operation of the SRS. I did, in fact, put the '05 passenger seat pressure sensor into the '03 SVT passenger seat, swapped the '05 side air bags into the '03 SVT front seats, and put the seat position sensor from the '05 onto the SVT driver seat track. It was a lot of aggravation, and took many weeks to figure out the wiring for both the '05 and the'03 SRSs.
RoosterST here on FF, posted a wiring diagram for the '05 SRS. If you can't find it, let me know and I'll get you a link to it. Finally, as you may already know, the SRS (air bag) light can not be read, or reset by just any OBD II scanner. Ford dealers have the necessary software, but because of liability and federal safety regs, are very reluctant to do much with the SRS. There are some independent shops who have the special software, and may be amenable to reading your codes, and clearing them once the issues are fixed. I did look into the simulators which, I'm sure you know, are sold for "off road use only". I found several places from which to order them, but chose not to risk being injured, or liable for injuries to a passenger on account of not having the SRS. Good luck.