Why do I always find the answer after posting? I did an exhaustive search beforehand with no luck. I changed my Google search slightly and BAM!! I found this PDF in my search finds:
http://www.yellowjersey.org/Suntour21.pdf
Page 10 outlines what each marking means, but here it is for the short answer: The UL is for ULTRA-7 index cassette. These are narrow spaced. The RE is for standard spaced Winner Systems, 6 speed. The P is for non-indexed friction shifting, regardless of the cassette. I have attached the document for those who may have the same technical questions as I did. Suntour is pretty finicky it seems on what will and what won't work with each other.