Looking at the instructions to upgrade Exchange 5.5 to 2000 it shows 4 steps.
Disconnect Unity from x5.5.
Upgrade x5.5 to x2k
Create AD OU
Reconnect Unity to X2000.
No mention of installing/upgrading Exchange Admin tool on the Unity server. On an existing exchange site, off-box, implementation I am assuming the Ex Admin tool needs to be upgraded to the System Manager on the Unity server.
Is this correct?