If it helps, when you see Gutermann's "sew all" thread in the shop, that is nearly always their "Mara 100", which is Tex 30. Mara 70 is Tex 40. The Gutermann's thread type #'s don't have so much to do with the size/weight of the thread as they do with how many meters are on the spool. For the mini-cones that you normally find, Mara 100 has 1000 meters, Mara 70 has 700 meters, Tera 40 has 400 meters, Tera 80 has 800 meters... you get the drift. (Oh, and Tera 80 large cone would have 8000 meters, Mara 70 large cone - 7000 meters, you got it!)
Anyway, most any Gutermann thread you find at a Jo-Ann's or other similar sewing shop is going to be Mara 100, Tex 30. They usually won't carry any "sew all" in a heavier weight because it's not really necessary when you're sewing a blouse or quilting. In fact, you can get by just fine with outdoor gear with Tex 30 weight thread, so don't be too put off by it. The reason I carry the heavier version, Tex 40, is simply because our end use sees a bit more stress than your average dress or blouse, and I like to err on the side of caution.