Tow-Rax offers the Utility Tray, part # TWSPOTS that sounds pretty much what you're looking for. The tray is 33-2/3 inches long and 5-1/4 inches deep, and would be a good choice for keeping your toolbox organized, and keeping frequently used small items like screwdrivers and wrenches easily accessible.
If that Utility Tray/Tool rack is too large for you, A sliding tray like the # UWS060035 you referred to might be a good choice. It'll work on UWS toolboxes that have the 20-7/8 inch width... view full answer...