Technical Difference between "Edmunds Custom" and just "Edmunds"?

I just bought a set of Edmunds 8BA heads off eBay. These are just marked "Edmunds". The heads I have on my '51 are marked "Edmunds Custom". Does anyone know if this is just a cosmetic difference or does it represent a change in design?

 

From what I've seen, Edmunds Custom predates just plain Edmunds. That being said, due to his going out on alcoholic binges and not paying the foundries, Eddie had to use many different ones over the years, which resulted in many design changes. This was told to me many years ago by a lifelong L.A. inhabitant.