I would use a digital caliper and measure what you have but I believe that Peugeot used an unusual sized 22mm stem as did many French bikes. If it is from the 1980s that might be different. I would not order anything especially for a French bike before measuring at least twice. Everything I have taken apart on Peugeot Px10 has not been a standard part. You can buy a good enough digital caliper from Harbor Frieght for under $20 and way under if it is on sale which happens often. You are going to need it for your bike. Roger