I can replace an army with a corps from the reserve box provided they are of the same nationality. The nationality table indicates there are 4 Axis nationalities (German, Waffen SS, Luftwaffe, Italian) but then the rule beneath provides that Waffen SS and Luftwaffe units are considered German. Does this mean that if a German infantry army is eliminated, I can replace it with a Waffen SS corps, since they are both German?
If this is in reference to rules 9.32, 9.323, and 9.35 the answer is "yes" - the wording is literal. It's largely an academic question in practice. I can't imagine why the Axis player would be keeping the strength and ZOC capability of an SS Panzer Corps in the reserve box. Most games I have nothing at all in reserve or a single infantry corps at most.