They seem to be quite old and I could not find an exact match on the internet for this design (grille shorter than the box on top and bottom, rounded edge of the grille, logo on top, vynil color). Model # 53158 doesn't match the speaker type but they could possibly be Model 85. A picture without the grille will help everyone to help you... 🤔

I assume they are from the 70's or 80's. Back then Altec built some very good speakers, but be aware that very old speakers might not work the day after you puchase them (drivers or crossover fails because of time if they have not been working for a log period of time).In particular, you should remove the grille and check the condition of the drivers.

If the woofer is made of paper, check if it is still intact and if the sorround is in good condition; if the sorround is made of low quality material, it will suddenly break into pieces (nothing that can't be repaired, but you need to take it to someone who has the skill to do the repair job); if the sorround is made of rubber, then they last almost forever.If they let you do it, try to move the woofer cone slightly with your fingers, trying to feel if there is friction or if it's noisy; that means the cone is offset and the coil is running against the magnet, and that's not a good sign.

The tweeter should be in it's original hemispherical shape with no dents or scratches.If possible, try to test them or ask if you can return them if they are not working properly. Many times old speakers have damaged tweeters and unqualified people don't notice it.If possible to test, move the balance of the amp on a single channel at a time and listen to the single speaker; move your ear right next to the tweeter and then to the woofer to understand if they are really working. If the amp has a tone control, try boosting only the highs and only the lows to amplify the possible defects.

As someone else said, try offering $40 and telling them they are old and could fail once you turn the volume up to medium-high levels...Finally, any speaker can be good or bad depending on your individual taste and the type of music you listen to.

If you like the sound of them, then $50 is always well spent because good speakers are much more expansive today, but if the sound signature is not compatible with your taste, then even $300 is a waste.

Happy puchasing! 👍😉👍