I think his hair didn't look that great when he was doing TJ Hooker. I thought the hair looked pretty natural during the underwater scenes in IV. The way it parted as he swam. I don't know what they had for men going bald in the '60s. I remember watching an ep of "I Love Lucy." Where Ricky was afraid he was going bald, and Lucy was tired of hearing him complaining so she went to some hair shop and they had some wild ideas of how to grow hair again. And she came up with some of her own wild ideas and used them on Ricky.