Originally Posted by
DannoXYZ
Nope, unfortunately for you, the mid-'80s FH-6208 600EX 7-spd Uniglide hub is the last of the 2nd-generation screw-on freehub-bodies. It cannot take the 3rd-generation bolt-on bodies that uses the 10mm hollow bolt.
Are you sure? I have taken apart many Shimano 600 and Dura-Ace hubs, and I have only seen what is shown in the picture in the 2nd generation Dura-Ace hubs. I think that with 600 Shimano went directly from the first-generation press-fit body to the 3rd generation 10mm hollow bolt.
I have upgraded several older 600 Uniglide-style hubs to Hyperglide freehubs. No issues.
I have also upgraded several of the first-generation 600 press-fit hubs to 8/9/10 speed Hyperglide freehubs, without using the hollow fixing bolt. Bolt really isn't needed as the hub axle and cones holds everything together.