Bicycle Mechanics - When did Shimano start making cassette hubs?

I'm looking for an older roadbike that I can convert to a single speed the cheap way (remove the cassette and throw on some spacers and a bmx cog). I see lots of Shimano 600 equiped bikes that are 5,6 or 7 speed. I think the 7speeds use cassette hubs but I don't know about the older ones. Anyone know when Shimano started making the cassettehubs?

Since you're converting to a single speed, you don't need a freehub. There are single speed freewheels that can be screwed into a freewheels hub.

A free-wheel hub would work well. Center the hub on the axle, redish the wheel and a freewheel will screw right on. One of my fixed wheels is set up this way, using an old Dura/Ace hub

Spining a track sprocket on an old 'freewheel type' hub will work to make a fixed but use lock tight because back pressure on the pedals tends to unscrew this setup it will work fairly well and has for many folks. A track hub or flipflop will have a second smaller left hand threaded portion that a lock ring screws on and prevents cogs from unscrewing.
http://www.sheldonbrown.com/fixed/index.html

or more specific http://www.sheldonbrown.com/fixed-conversion.html
And http://www.sheldonbrown.com/deakins/how-to-fixed-conversion.html

I'm looking for an older roadbike that I can convert to a single speed the cheap way (remove the cassette and throw on some spacers and a bmx cog). I see lots of Shimano 600 equiped bikes that are 5,6 or 7 speed. I think the 7speeds use cassette hubs but I don't know about the older ones. Anyone know when Shimano started making the cassettehubs?

I think it was in the late '70s. But they also made freewheel hubs into the late '80s. If a hub is 5-, 6-, or 7-speed, it might be either freewheel or freehub. But I think starting with 8-speed, only freehubs were offered.

Gonzo Bob is right, Shimano made freehubs as early as the late seventies. The cheap way of doing this is to find an old BMX with a flip-flop hub. (See capsicums post) Make sure the roadbike you buy and the BMX bike you buy have the same hub flange diameter. Re-spoke the BMX hub into the road wheel then respace the axle. The flip flop hub will allow you to run 2 different freewheels.

Thanks for the help! I'm picking up an early 90's Chesini (Italian steel) tommorrow, should make an awesome single speed!

They sell the flip flops for roadbikes now. one side is a single speed freewheel/hub(able to coast) the other is a fixed gear(the pedals will keep turning as long as the bike moves).
Make sure your dropouts are more horizontal than vertical so that you can adjust the chain tension, if it has vertical dropouts you will need an eccentric hub.

I had an all steel 5spd Shimano freehub on my *mart bike back in '82