I have a Hurth HBW150 which takes 0.63 quarts of Dexron III. I also have a Hurth HBW150A which takes 0.59 quarts.
Here are the numbers for different Hurth gears
HBW 50 and 100 - 0.44 qt
HBW 125 and 150 - 0.63 qt
HBW 150A - 0.59 qt
HBW 150V (V-drive) - 1.03 qt
HBW 220, HBW 250 (25M) (nee 20) - .79 qt
HBW 360 - 1.50 qt
HBW 360A - 1.60 qt
HBW 450 - 1.90 qt
HBW 630 - 2.1 qt