Ebay is a possible source, though when I just checked I did not see any servicemans reference books shown.
Caterpillar Legendary Literature, is a reprint offering by CAT, the attached link is 30 pages of listings, your tractor is in there somewhere a few pages in. When I looked it up on the CAT site, there were no corresponding links to this .PDF file with most if not all the equipment they produced. Not sure whats up with that. You should record the serial numbers of your tractors and get the corresponding books for them, the attached link does cross reference books to serial number production runs, so you may be able to pin point what you need. Typically, around or not long after your tractors were built, the 3 books to have for these were the Operators Instructions, Serviceman's Reference Book, and Parts Catalog. These were the titles for many years, not sure about yours or earlier tractors, and what may be different, but years back CAT did not publish these for some time, Midland Press used to reproduce older manuals, some years ago, CAT took it back in house, and started this legendary literature program, offering all the books for older tractor, same price for each book, and they did list a catalog of the books available, so I believe this should be correct from what I read years ago, its just that I cannot find any links to order from. The attached file has abbreviations, states the size of the books, pages etc. it might help you track down what you need, and hopefully this program is still intact