Okay, then it sounds like the 540c enabler will still be the one that needs to be used. The memory map should be the same for both systems since they have the same ROM sizes and they both accept the same RAM modules and have the same maximum RAM amounts.

I'll also have to run TattleTech on both the 540c processor and the 550c processor to get the ROM versions and sub-versions to see if they match. The Apple technical specifications list the ROM ID and Ver for the 550c, but strangely they are not listed for the 520, 520c, 540, nor the 540c.

Finding a copy of the installation media for the 550c is proving to be extremely difficult. I have had no luck thus far, and apparently that installer is the only one that contains the Powerbook 550c Enabler