The book is very useful but I think there are online options too. I haven’t used those but others can perhaps let you know.
My description of the parts book wasn’t quite right, ,it actually shows all the part numbers immediately following each diagram AND has a big sequential list of numbers at the back, cross-referenced to the relevant diagrams. So you can either find the number of a particular part you need, or, if you have an Unknown part with a number on it, you can find out what it is and where it goes. It also lists RHD/LHD specific parts, how many of each part are required, and superseded part numbers (at the time of printing).