Update:
Here is a shot of the underside, showing the addition of the "scale" bolster:
(...this looks to be the same as what's on a US Hobbies brass hopper I've been working on.)
Here is the "original" Athearn truck:
...nice enough and sprung, but being plastic, it doesn't weigh anything.
Here is the metal, sprung truck I had on hand:
I don't know the make, but they are nice and heavy.
There you go...
Mark in Oregon