When I removed rod, mine flopped around so I too thought it was not functioning. I pinned it up and it made a huge difference. With it pinned up and my Chevy 1 ton wheel cylinders, it will lock up the rears a little durrng hard stops in the rain. I still it like though.
I "believe" all the drum brake 2500s had the level sensing propotioning valve. The others may have a standard proportioning valve.