Manuals which are still in print are copy writed materials
That's the usual problem with finding them available for the taking on line. If a individual person sends you a PDF copy of their owned (or stolen <g>) version of a manual it would be pretty hard for the manual's owners to know or to do anything about. But someone offering it free from a website is an easier target.
I wish I had bought mine on-line. I was in a rush when I needed and Auto-Zone charged me $38. for it. On line I see it's $20. less. <g>