How to secure a plastic toolbox into the bed
 

Hey guys, first time poster here. I have a 2001 regular cab Ranger, with a plastic toolbox in the back. The problem is, the person I got it from previously only had it secured with a chain attached to a s-hook and no lock for the top, meaning anyone could open it. I haven't really had the time, but I recently stopped by Walmart and picked up a nice padlock to lock the top so it can't be opened, but I'm fairly paranoid.

The problem is even though the top is now secure, it still isn't properly secured into the truck, and any two people could just unhook the chains and lift it right out of the bed. What is the best way to secure it that doesn't take too much technical knowledge? Although I prefer not to drill into anything, if I absolutely have to I will I guess.

You can use padlock or cablelock(bicycle) instead of "S" hook(s) on the chain.

Drilling it and using mounting bolts would be the cleanest look.
You could cut a piece of exterior rated 3/4" plywood to fit in the bed, a bed liner, and bolt/screw tool box to that, it wouldn't move around, no holes in the bed, AND it would be very hard to carry away, lol.