Thanks for the help so far--after managing to remove the cassette from my wheel, and googling for a while, I realize that my terminology was all wrong (as you pointed out anotherbrain)! Sorry for the confusion.

So I definitely have a freehub with a cassette (held on via splines), but as on the park tools website it's an older model with no lockring. I had to use the two chain whip method to remove the outer most cog, and then the rest of the cassette slid off the freehub. So I think my best bet for a SS conversion is to use a BMX style cassette cog and a series of spacers to get the chainline right. Then cap it with a lockring, as in the surly SS conversion kit. Does that sound right? I'm wondering though, if a lockring will fit on the treads on that freehub, or will I have to use the original outermost cog (or a different kind of lockring) to hold the spacers and cassette cog on. Thoughts here?

Thanks for bearing with me!