It's 7spd Hyperglide, I bet. Show me a stock 6spd bike with dual pivots.

And changing a Uniglide hub to Hyperglide is a piece of piss anyway. Unless you're talking about a Dura-Ace AX hub, but I've managed even that. And anyway, it doesn't matter cause I'd bet my left nut this bike's HG.

And FTR, Shimano's freehub is the best design to be found in such numbers by a very long chalk.