.30 carbine die set mystery

So among the die sets I picked up at a recent estate sale is a .30 carbine set that has me baffled, partly because I don't reload this caliber and partly because of the dies themselves. The box says it's a 3-die set, but there are four dies in the box. Here are pictures of the box, both ends of all four dies, and the decapping rod from the far left die.



Obviously the sizing die on the far right is missing the decapping/sizing rod, so that needs to be replaced. And the decapping rod from the die on the far left is different from any I've seen before. Looking at the lettering on all four, there aren't three that look like they go together. I have no idea what I have here. I've written to RCBS and tried to describe the dies, but the email function won't let me send pics, the auto response says it may take up to 10 days for them to get back to me, and my curiosity is driving me nuts. I'm looking to sell these for below market value because I got them very cheap, but I have no idea what that is, and the rules of the Trading Post forums say "best offer" threads are verboten.

Any help out there? Thanks heaps.

edwardware said:

I'd call it a decap and flare die, used after sizing, like you'd need to load cast bullets.

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That's what I was figuring. So do you think the die is somewhat universal, and one buys different rods for different calibers?

So was there anything that threaded into the top of the sizing die?

Thanks a ton for all the info.

mkl said:

On the old die sets they did have internal threads, but I never tried to figure out what they were for. As received in the RCBS box, the sizing die just sized. I have a couple of sets in .38 special.

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Thank you all VERY much. Now I at least know that I am selling a complete set of dies that is not missing any parts.