We regularly receive requests like: "What transmission fluid should I use in my Hurth transmission?"
I ran across this reference the other day: http://www01apps.zf.com/kst464/ZF_InteroeleV2_manager/Work/2010-04-01/TE-ML%2004_en0700.pdf (http://www01apps.zf.com/kst464/ZF_InteroeleV2_manager/Work/2010-04-01/TE-ML%2004_en0700.pdf)
Our Hurth transmissions are ZF50 or ZF100, so use the 04D list. It's an older pdf file, which only shows Dexron III. Dexron's up to probably 7 or 8 these days. The Dexron fluids are backwards compatible, but that shouldn't matter since you should remove all of your old fluid before installing new fluids anyway.