OMG! I know it looks like a few years since anyone's responded to this thread, but I was a member of one such club growing up in the 70s. My father got me into it. It provided a number of different models - cars, military vessels, ships (I had a Viking ship), jets, spacecraft, etc.
I received one model from that club that my dog chewed up and I've been searching for another ever since. I believe it was a jet (may have been a spaceship) which looked similar to a stealth jet. It was molded in a dark brown plastic and had a yellow translucent window at the cockpit. What really stood out about this model is that it had a smaller version of the jet which fit inside a docking bay at the rear. You could pop it in and out. It's the only piece I have left.
If anyone knows where I might be able to find one, I would appreciate it. I've searched Ebay, but I come up empty-handed.