There are still plenty of freewheels around, both new and used. And if you have hyperglide, the world of gearing is yours. But what to do with my Uniglide? It has gone the way of betamax. The only good use I found for wheels with Uniglide is to use them for SS conversion with spacers and a cog.

Your thoughts?

Well if you have a uniglide hub with the bulge on cluster side, not a silent clutch free hub. Then you can find a hyperglide hub and you can take the cassette body holders( or whatever they are called). You can swap this onto your uniglide hub. For about 30 bucks you can pick up a hyperglide hub. I know there is one on ebay right now. Also sheldon brown has a tutorial on how to do it.

Well the freehub section is extinct, but the hub body is not. I replaced the 6 speed UG freehub with a 7 speed freehub (HG) added a 7 speed cassette and reused a beautiful set of Ritchey Advantage wheels with Shimano hubs on a vintage MTB build. If you're locked into 6 speed, I'd use the spacers from the old six speed cassette and use six gears and spacers to make a six speed set up on an HG freehub. It's all good. BTW, those 7 speed freehubs are available on many old, rigid fork MTBs that sell at yard sales for $15. You might be able to find one, use the freehub for yourself, then sell the components and the frame and make a nice profit.

What is the biggest concern with uniglide? Lack of cassettes?

I am about to build a wheel right now with a uniglide hub, so any thoughts is appreciated...

Yes, lack of cassettes. Personally, I wouldn't put in the effort to build a wheel around a uniglide hub.

Totally agree, once the ol' Uniglide cog(s) are worn out, simply move on. Or mothball it now for a collectible model of bike that you want to keep it OEM specific.
I have found and stumbled upon abandoned 7-spd HG freehub bodies that I have salvaged for swapping Uniglide 105 and 600 freehubs. A few will take both UG and HG cassettes. So, I'm all set, I'm sure others have done similarly.

The problem with Uniglide is finding replacements for the outer, threaded cog, which is unique. HyperGlide cogs for all the other positions can modified with a file or Dremel tool to fit the Uniglide body.

Say does anyone have a hyperglide 7speed body? PM if you do, the bike building the wheels I am using are new just have uniglide hub on them. I think at some point I will upgrade them.

+1 on several fronts. Some later Shimano 600 hubs with HG can easily be converted to a freehub like the poster above mentioned. And, you can go farther than 7-sp with a longer axle and re-dishing. I had a 600 tricolor rear done by LBS, $35 plus parts, and it was worth it to be able to upgrade the entire bike.

As long as ome of those older hubs have the great re-packable bearings, they are worth reconfiguring, as they are nicer looking than many modern wheels, the hubs can be packed, and the bike retains it's traditional look.

I currently have a nice collection of usable UG cassettes, loose cogs, and the small screw on first cog, and no UG freehub wheels. I'll be glad to, swap, barter, let go at a very reasonable price, etc.