http://www.practicalmachinist.com/vb...95/#post893695

Which from http://www.fuchslubricants.com/renolit-ep puts it as a slightly thinner than normal/common type grease.

Plus from a couple different posts I found, the general consensus is a general grease designed for gears. Given the age of the design, and the fact there's not really any specific requirements, I wouldn't personally be worried about using the exact grease.