Combination valve photos

Been meaning to post these for a couple years but finally clearing off the bench where it's been laying.
Nothing much to say about it, was just curious what it was like inside so cut one on half.

Notes: this style (40A) is at least on 86 3/4 ton trucks. Unsure of true application specifics.
It does NOT have an opening on both ends like the 1/2 ton ones I've seen - the green Sharpie'd channel is something I drilled entirely. There was not a channel there prior. This is the leftmost horizontal channel in most of the photos before it hits a vertical channel.
My 80 1 ton also has openings on both ends.
I lost the spring that goes over the Space Needle looking part so it's not pictured.

Cool!  Those may come in very handy at some point.