I'll speak of something I know, and work with daily. If I decided to build, say, a 2007 S60 Volvo, to provide a"Factory" service manual, these days, involves a subscription ( which is not even remotely cheap) to the factory website, and internet access. As far as I know, there have been no paper books for at least a decade, and Volvo does not produce anything on disc.

Alldata and Mitchell provide an accurate aftermarket source for the info needed- Alldata is the actual factory info just transferred into their system, and Mitchell takes the same info and "washes" it into their standard style. They are both available by subscription, although the professional system is $200 per month or so. Disc may still be available, but again, a subscription is required. As a professional who works with these systems daily, either one should be seen an acceptable alternative to the factory requirement.

I'm sure there are discs available from the aftermarket. As to their accuracy, I would think Haynes quality. It will be ripped from a legitimate source, but how complete?

I still say its gonna be troublesome, and maybe moreso than searching ebay for a Pinto service manual. Probably no more than ordering a new factory Pinto fender, though.