that's a smart thing to do. I have the serial and model numbers in my truck, in a file cabinet in my house office, and on my computer.
My set up:
-2007 Chevy 2500hd 8.1l 4x4
-7x18 enclosed trailer
-Grasshopper front mount 61", gravely 52"
-36" Gravely Walkbehind, 21" exmark push mower