While I'd have to see a photo to have a really educated guess, and acknowledging that wood does splinter, I can make a cople of guesses as to why there is wood in the bed:

1) First off wood is cheap, readily available and readily worked. In a "make do" situation, it will do when a better material exists, but is not available.

2) The wood is acting as a spall liner inside the armour. While it splinters if penetrated, it's also soft enough to absorb metal flakes that spall off impacts on the armour.

3) It may be acting as a low weight internal support for part of the armour system. If the armour is, say 1/4" armour plate backed up by sand or concrete, a wood internal layer acting to hold the sand or concrete makes sense.

4) It may not be part of the armour system and there simply to support other items inside the truck bed, ie it's easier to mount ammo racks or seats or shelves to the wood than the armoured shell.

5) It may simply be there because the crews thought it dressed up their ride or provided a slightly less hard internal surface if they were thrown into it. Don't underestiamte what crews will do to dress up their vehicle even if it seems stupid or compromises some of the operational aspects of the vehicle or them wanting to get rid of painful protrusions in a space that is cramped and has several people moving around it in combat.

These are just some suggestions, I don't know if any of them are the actual reasons, though.

Paul

While using a thick wooden backing at the inside of the box, the effect of the hot metal spray is reduced, if not stopped.

my guess is you know much of what you speak of.

If the wood was on the _outside_ it would have more effect as it would cause the detonation too far away from the steel for optimum penetration