Gary Boyer wrote:

Has anyone tried mounting a magnet mount hf antenna (Hamstick) on the
top of a metal toolbox ...

No, but does your truck have stake pockets? There's an outfit that makes
antenna mounts that fit in the stake pockets of pickups. I got one for my
Ranger to mount a 10M Hamstick. Works pretty well and is a rugged mount. It
would probably handle something a lot bigger than the Hamstick. Can't
remember the name but they advertise in QST. I had tried a magmount in the
middle of the bed but couldn't tune the Hamstick there. I'd guess you'd
have the same problem due to the cab. Using the stake pocket mount (in the
rear-most pocket on the pasenger side) it works great.

OTOH, a friend of mine runs a screwdriver antenna mounted to the rear wall
of his toolbox in his big Dodge PU and it seems to work OK...

73.. Mark AA7TA