heedcase wrote:

I need to replace the chain on my 85 Fuji Del Rey. I would like to
purchase online so I can have more choices. I don't know the proper
size to select.
It has a Sugino crank with 52/42 chainrings and 6 speed freewheel. How
about a little help.

As others have said, any chain suitable for 6, 7, or 8 speed. But size
also includes length. Most any chain will be too long for your bike,
and needs to be shortened a few links to match your existing chain.