Looking to find an OE 1973427 for the original 1111973 69 H/O distributor. I checked it and the diaphragm's toast. Pretty sure it's the original as it's numbered "427". I know, it's probably as easy to find as the 973 itself.

Not sure what the service replacement distributor 989 used. Probably the same.

EDIT: Sorry, put this in the wrong place. But can't delete this one. Moderators, feel free to pull the plug on this one.

 

That's a tough part to find. I saw an NOS one on ebay a few years ago but it went very high. I've got an NOS 1111989 distributor boxed up in the basement. If I can find it, I'll check the vacuum advance for a number.

In the meantime, you might try supercars unlimited. I think they may have a repro.