Ditto on the software thing. I manage 7 crews with an Excel spreadsheet and have 3 of the large 4X8 shower board (wipe off board). List crew and route number, vehicle number, crew members and assigned equipment by number. Divide in to days of the week, or daily or whatever.
Write in with black marker where you need too.
It will help you organize your shop, and you better have a shop with this many crews and expect to have a 1/4 to 1/3 time mechanic or equivalant.