Dug this out of the garage a few weeks ago and now finally getting around to posting this. I remember this piece from my childhood.
I guess it fits slightly better with the flatbed removed.
The container actually comes with a truck. But I have yet to find it. There are notches on the bottom of the container that fit on the rear of the truck. [I accidentally stuck my hand in the photo before it was finished and too lazy to dig this back out to re-do since these photos are a month old.]
The back actually opens. Inside are a few LEGO bricks that have been sitting undisturbed for well over a decade.
And here it is with the Tomica Capsule Subaru Sambar that I found on the same day.