Latest manufacture dates were around 91-92 IIRC. They expired late 90's at best.
If they are bloated then they are obviously expired. Not sure of the nomenclature but the filters on these masks deteriorate and breakdown in a way that you could breathe in some of the (broken down) particulates and become poisoned. The M17 Masks (and at least the Mil filters/ pork chop style) are a thing of the past. Not sure if any companies are making a replacement filter for that mask but I doubt it with ever thing going to 40mm NATO thread.
I would suggest you DO NOT use these for your own good. Read: destroy them