Most likely those came from a "stereo in a box."
Google search for that model number turned up nothing, which is why I doubt they were standalone speakers. You could try removing one of the woofers or tweeters to see if a brand is stamped on the magnet.
Don't get your hopes up too high for those. As someone who grew up with a budget that only afforded me Radio Shack's finest when they were on sale, I can spot a few warning signs. The cabinets seem to be particle board, and if that's the case you might not even want to remove a screw since that stuff strips way too easily.
Also, these were probably meant to be sealed enclosures. The 4 holes in the front most likely held rubber "plugs" into which the grilles were mounted. Either an adventurous child plucked them out or they just popped out when someone went to remove the grilles (I have seen that happen first hand). Regardless of how it happened, it will reduce the bass response of the speaker and it will allow more excursion than it was designed for. If you do like the way they sound, just don't experiment with putting a lot of power to them.
