Wanted: Shimano rear wheel 6 Speed cassette body 700

Okay, here's what my bike shop guy told me to look for.
Shimano Rear Wheel 700 with 6 Speed cassette body.

So really the wheel I've got is fine I just need the cassette body or whatever it's called that actually makes the wheel go round. But he reckons I won't find one of those without buying the whole wheel.

I get the impression that a 7 speed would be compatible. Is that right? If so then I'll buy that instead.

http://www.hilarystone.com/cassettes.html

this is not what you want, but he might well have what you want if you email him.

The only 6 speed 'cassette' bodies were uniglide hubs. if that's what you want then I have a whole rear wheel in very good order. You would be very lucky indeed to find a uniglide splined freehub tbh.
However If you are referring to a 6 speed freewheel that is not a cassette as it screws directly onto the threaded section of the hub. These hubs/wheels can still be bought brand new for not a great deal of money in any case.
If you can say for sure exactly what you have now (a photo would help if you're not sure) and what use you want it for as it might well be better/cheaper in the long run to upgrade to a 7 speed cassette wheel in any case.

I posted this and then went on holiday. A late thank you for these replies.