For parts lookup, either register (free) with your cat dealer, or, do like I did and register there, and with AVSPARE .com. It's free, too.
Once registered at AVSPARE, from the home page, enter your model number and pick your prefix.
Next page will have a machine systems listing.
Pick your system, and the next page will have parts listed, with service info below. Not every piece of service info is in there, but there's a hell of a lot.
As stated before, individual segments of the manual can be bought separately...the electrical schematic isn't on AVSPARE, but, i know my Cat dealer will print one out for less than $50 (rather than waiting for a printed manual to come by mail).