Yes, all terminals should be isolated from the case. If you have a digital camera, it would probably be a good idea to email me some pix to make sure the alternator is the same as mine. The Bosch part number on my case is 0 120 400 847.
So I pulled the alternator. So you want me to test resistance between DF and the case, D+ and the case, and then D- and the case. If it's all 0 (infinite), then you want it? I will test it tonight...I didn't have your note handy when I pulled it.