I'm busy fixing the track car so I haven't gotten to doing this fluid swap yet. Here's the info I've gathered on the fluid.
I tried contacting ZF for information on differential but they denied it was their product.
The procedure:
https://www.newtis.info/tisv2/a/en/e...-drive/Pk9i8JT
In searching 83 22 2 365 987 it appears to be a 75W-90 oil