I checked some of mine.

Strangely enough the newest Pyrex I bought says made in the USA. It's a see-through glass pie dish.

Another little casserole dish with a glass lid is one which must be about 20 years old and has a star like symbol and the name Corning P4 but says "cerammed" in Australia.

I did some reading around briefly after you posted and it sounds as if it's the impurities in the product that can cause it to explode or shatter. Not very good is it?!

Those old vision saucepan sets were great. They didn't seal very well I thought but I really liked using them, thinking they were the healthy alternative at the time to what we aussies call Aluminium.