Hey Woody,
I asked somebody on a French MB board, and they sent me a link to an owners manual for 1978. It's still hard to work out, but it basically says that when you're replacing the version 1 rear struts you need a full tank of fuel (or extra weight 1 liter= 1 kilo) and a weight of approx 150 kilos on the rear floor. If your wagon has uprated suspension (??) you need 400 kilos on the rear floor. Voila!
Don't ask me what a kilo weights in groats, or pebbles or whatever you guys still use.
Take care
Giles