Does Dorman or somebody like them make replacements? Mine are pretty dry rotted away.

Depending on the the plug size/type itself they can total to a rather expensive replacement.  For instance on my Sunbeam Tiger the club has "Trunk Plugs" that are about 6 or 8 plugs.  They cost about $60 for the set because they are a slightly odd size and some people want an "exact" replica of the original..  Even at $3-$4 a piece for generic pugs they can add up when you need a large number of them.  I've resorted to pulling the size I need out of newer cars at Pick Your Part yards. They seem good as new and are a lot cheaper.

There are plenty of various size plugs, including 7/8" at (ford pinto body plugs on E-gay) right now! E-gay should be the first place you look for hard to find pinto parts. I get a kickback for that statement. Tell them I sent you.