As background I have fairly extensive experience with ZF transmissions and ZF states that the transmission fluid should be drained and refilled every 80,000 kms or 50,000 miles. I will be changing mine in 10K miles since I am at 40K right now.
BMW also stated lifetime fill until transmissions started failing then changed their policy to every 100K miles which is half of what the transmission manufacturer recommends.
I provide this as information so that others might understand that there is no such thing as lifetime fill unless the lifetime is 100K miles which you are already at.
Lifeguard 8 is easily obtained from places like CTSC in California for around 9 bucks a L if you buy a dozen L which is what I will do since this trans will take around 5 1/2-6 to drain and refill.
Genuine ZF Parts
Please post where you get your diff and transfer case fluids. At this point I am thinking of using MOPAR products which are rebranded for them by some manufacturer...