Detailed info for all Dexron ATF fluids
 

Here is the link if you want : General Motors Oil Specifications - oilspecifications.org

I though this might come in handy for someone. It did for me since I have a bunch of DexronIIIH and was wondering if I could use it in my 03 TC. Sure can.
Automatic Transmission Fluids

Dexron Type A, Suffix A Specification introduced in 1957. It requires the oil to meet certain limits regarding its kinematic viscosity.

Dexron IID General Motors Dexron®-IID Specification. ATF issued in 1975. Contained ATF cooler corrosion requirements not listed in Dexron® - II. Dexron IIE General Motors Specification Dexron®-IIE. ATF issued in 1991 requiring improved low temperature performance compared to Dexron®-IID, 20 000 cP at minus 40 °C.

Dexron IIIF GM specification for Automatic transmission oil introduced in 1994. Successor of Dexron IID and IIE. Dexron IIIG Successor of Dexron III(F) automatic transmission fluid. This has the same low temperature characteristics as Dexron IIE, but with modifications to anti-oxidancy and friction material. Introduced in 1997.

Dexron IIIG
Successor of Dexron III(F) automatic transmission fluid. This has the same low temperature characteristics as Dexron IIE, but with modifications to anti-oxidancy and friction material. Introduced in 1997.
Dexron IIIH Dexron III licence H was introduced in June 2003 to replace the Dexron III G fluid. It has an oxidatively stable base oil (group 2 or group 3). Oils according to this specification have longer maintenance of friction properties and anti-shrudder properties, better foam control and a longer fluid life.

Dexron VI Specification introduced in 2005 to replace Dexron IIIH. This specification requires better stay-in-grade properties, oxidative stability and anti-foam characteristics. Oils meeting this specification can be used with extended drain intervals and are energy conserving.

I dont think Dex 3 is the right fluid.

All the BMW part numbers for the correct ATF to use in the GM A5S 390R transmissions have been superceeded and the latest one translates to Dex 6, which most sources say is not replaceable by Dex 3 (but Dex 6 is backward compatible with 3, IIRC).

Dex 6 is what I ended up using in mine (trans)

EDIT: duh, I r stoopid. Didnt see you meant for the TC, which is the transfer case I assume?

If so, yeah, Dex 3 is what I used as well in a pre-Xdrive 4.6is TC.

Yeah I meant the transfer case with the TC .Thanks anyway.