Nobody is going to spend 20 or 30 years in business compiling that type of information and then just give it away. That wouldn't be very smart. Some of the Factories don't even trust some of the attachment manufacturers that have been in business for 40 - 50 years with all the hook-up info.
Also, a lot of them have non-compete and confidentiallity agreements with their suppliers that won't allow them to give away the attachment mounting info. Many of the Factories won't even share that info with their own dealers.
It seems crazy, but it's true.
It takes a long time to build up industry wide relationships with all the different people in all the different companies who control that type of information. And then there are hirings, firings, buy-outs, restructuring of companies, etc.
If you were Ford, would you give the plans to build a Mustang GT to Chevy.
That's how they make their money.