Steve, browse to this pdf file to see what GM transmission we have:
http://www.automaticchoice.com/Catalogue/v_index.pdf
on the left menu, click on 'BMW'
I changed output shaft seal, transmission drive extension and transfercase output shaft seal today.
While i removed drive extension to replace the gasket, i dropped 1/2 liter of transmission oil and i decided to change filter, gasket and oil too. Transmisssion is very dirty at 90K miles. I should changed it earlier. I drained out >7 liters totally and refilled the same amount of fluid.
I bought 2 gallons of Dexron-VI at dealer for $90 ($45 for 1 gallons <=> $11.25 per quart)
When you are at dealer part dept. just giving them part# 83220024359 it will comes up with new part#: 83220397114. This is exactly for our X5. The newer fluid is for newer X5 (E70).
Wondering Dexron recommended us to change oil while BMW says it's Lifetime.
Here are 2 photos of fluid:
