The current incarnation of the original K-25 Alpha would be my guess for the answer to this. And/or Big Bertha (originally K-23).

That E2X X-Ray was a mini-motored sorta X-Ray...and it's been gone a long long time I think.

Added after a quick look on Ninifinger: It's gotta be Big Bertha. She's in the 1966 catalog but the Alpha didn't come out until the 1967 catalog.

So, Big Bertha has been in production for 48 years!

(I'm assuming that it was continuously in production during my rocketry hiatus here....)

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Bernard Cawley
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