Hoppers commonly in fertilizer service today?

[packers#1]

For MRH's $500 layout challenge, I'm designing a layout based off the MRL's branchline to Harrison, MT. The sole industry is an elevator and fertilizer facility. I need to know what hopper cars are commonly used in fertilizer today in the west. Can anyone help point me in the right direction? I pretty much have the grain cars figured out, just need help with the fertilizer hoppers

[RockGp40]

National Steel Car Potash Service 3 Bay Covered Hopper or the larger Hawker Siddeley 4550 cu ft Cylindrical Hopper

You can find 4750s in it too. Usually ratty, may times patched over, 4750s.

[nkalanaga]

I assume you already have the June issue of "Trains" magazine with its article on MRL?  It had several pictures of the Harrison local, but probably not the answer you need.  They didn't say what was IN the particular cars shown...

[packers#1]

I assume you already have the June issue of "Trains" magazine with its article on MRL?  It had several pictures of the Harrison local, but probably not the answer you need.  They didn't say what was IN the particular cars shown...

That's actually where my interest in the Harrison Branch came from