Originally Posted by timcupery
If for some reason you have a 6-speed freehub body (I didn't know that they existed; I thought that freehub construction didn't start until 7-speed), and you install a new freehub body and get 130mm spacing, then yes, you'll need to redish the wheel. But not too much.
Just for information sake, yes there were 6-speed Shimano freehubs but their design was different from the current type. The freehub body was splined to the hubshell and held in place by the axle cones and bearings. It didn't have the hollow bolt current freehubs use.
So, even if his bike has a 6-speed freehub, it can't be just changed for a newer body.