Mount Item on Vehicle

Please point me to a forum thread (if any, couldn't find any so far) or help me with my dilema. I drive a truck around, I see an item (say some crate) and on collision with that item i want it mounted on the truck (imagine collecting crates along a map).

I understand mounting a (firing) weapon is a problem sometimes (or even a player). This must be simple. I am an artist, not a coder, perhaps that's why i can't find the answer alone.

Thank you !!