I was poking around with Google Images looking for tank car pictures
and came upon HOKX 650, which was a 5,800 gallon chlorine tank car --
I'm very happy to find this because I'm partial to Hooker and I have the
Mathieson model and don't care for that paint scheme...

prototype --
http://4.bp.blogspot.com/-yO_ZCDz4vPE/UUNekYfNeEI/AAAAAAAABro/SAUBU5MKrqs/s1600/Tank+car+traffic+for+the+island.++Modelers+take+note.jpg

model --
http://www.trixtrains.com/new04/24908.jpg

the blog page where I found HOKX 650 --
http://caboosecoffee.blogspot.com/2013_03_01_archive.html

It's amazing what you can find with Google Images :-)

Tim O'