FYI, I have a TDM800P (similar to the TDM400P but with two module daughterboards, but I only have one populated) running under 9.10 without problem. Unfortunately I cannot test this back to 9.04, but you should definitely try 9.10 to see if that will work. You'll have to migrate your dialplan from 1.4 to 1.6.2, but most of it just involves changing pipes to commas (Directory, VoiceMail, MeetMe, Record).
FYI, I have a TDM800P (similar to the TDM400P but with two module daughterboards, but I only have one populated) running under 9.10 without problem. Unfortunately I cannot test this back to 9.04, but you should definitely try 9.10 to see if that will work. You'll have to migrate your dialplan from 1.4 to 1.6.2, but most of it just involves changing pipes to commas (Directory, VoiceMail, MeetMe, Record).