Truck tool box/tonno

Anyone know of good tricks or seal/ant to keep water from leaking around/under those large truck toolboxes & getting under the tonno cover? Maybe some leakage is inevitable

Buy a Weather Guard box. This box does not leak.

I don't think the box itself leaks, but I'll keep that in mind.

Checkout Diamond Back bed covers It is the most well made bed cover I have ever seen No matter which type of door pattern you get the bed of the truck is accessible from the side of the truck They are well made and easy to install If installed correctly they are leak proof And the design makes the inside of the bed a good place to fasten metal bins or plastic storage boxes to keep your gear organized and easy to get to Without having to crawl Into the bed of the truck .

My toolbox is Delta & tonno is Access. Interestingly, the new toolbox came dirty inside. I asked around & someone said it's aluminum oxide--Now I have to figure out how to get that blackish gray residue out of the box

I'll consider.
I'm hoping to find a way to use the Delta box & Access tonneau cover that I removed from my old Silverado.

Do many of you use a toolbox / tonneau combo on your trucks? It makes it harder to setup & more challenging to water tight, but is nice.