The service manuals list the base model number they cover in the file title.
On my Mac I use a built-in program called 'Finder' and simply search the "Service Manual" folder using a model number or the first few digit of the model number.
If the model number is listed in the .pdf title "Finder" finds it for me.
Most of the .pdf's have searchable text too. Many of the service manual list the model number they cover inside the manual and once again I can use 'Finder' to search the contents of the manual itself.
Don't recall how I use to do it back in my Windows days as I switched to Mac's a couple years ago and never looked back.
Anyway that's what works for me. Must be a similar way to search the .pdf titles in the Service Manual folders on a Windows computer if that's what your using.