Well, I couldn't find any instances of anyone taking a GSM TCU and putting it in a 2006 vehicle, but I'm trying it anyway. Looking through BMW's ETK (which has alot more information then RealOEM, imho) from 01/2011 it appears that the parts will work for the vehicle.
I got TCU part 84109321088 along with FZD part 61319209579 from jimk late last year . Checking the part numbers in ETK shows them as valid for a 2006 E90 330i.
84109321088 doesn't show up in RealOEM and ETK because it's a part only put in new cars and BMW doesn't appear to sell brand new TCU's in their parts channels only reman units. The screen below shows that 84109231092 is the remanufactured version of 84109231088.
Digging into the parts use for that part number shows it as an acceptable part for use in a US version 330i E90.
Same with the FZD, 61319209579 shows usage as well in a E90 330i, shown below.
Both of these parts were manufactured around 05/2010.
I guess I'll see this weekend (if my bracket and other parts arrive on time) if it'll all work and if I can retrofit them with ISTA/P.