Good morning, Matt;
You seem to have found an unusual lens. From the information I have here, I can say that it was made by Olympus for Ponder and Best (manufacturer code 6), and it is a regular line P&B Vivitar lens; not a Vivitar Series 1 lens. I am surprised at how little information I can find about the lens, but there are a few other Vivitar lenses where information is also rare.
Take it out and try it. See what it does, and if you like the results you get on a print. You can even make your own resolution and contrast tests with the lens and compare that information with comparable models from other manufacturers. The main thing is, do you like the lens? If you like the results you are getting from that lens, then keep it.
You could be surprised. When I compared my Canon EF-S 4.0-5.6/17-85mm zoom lens with a Tamron Type B003 3.5-6.3/18-270mm zoom lens, I found that the wide angle distortion of the Tamron was less than the Canon. Try your lens and see how you like it.
