For Placer County – they have an interesting numbering system. First, you will want to click the Placer County Map Locator link below and find your area / parcel of interest.  The map locator will eventually bring up a pdf showing the Book and Page of your needed map.  I have included a link to an example map helping you to find the book, page and map type.  Open the “Placer County Map Key” pdf below to then get the map year.  Once you know the year of your map, then navigate the folders below.  At the end, you will see a list of maps.  Click around to get the map you want.  Placer County does not help with their file naming convention, BUT the files are in order (look at the title page).  Good luck and enjoy!