On eBay right now there is an old Leviton Sure Gard GFCI from 1977. I think this was the first Leviton design. Still has the red and black buttons. However, the outlets and buttons are sideways. I had seen one in the bathroom in an early '80s home. I think the more current design came around '85.
Also I have seen an old GE GFCI that was nearly identical to the old Square D/Bell but had the GE logo on it.
