Swiss bb with Motobecane from that era. Motobecane really loved Swiss bb. Replacements can be had, very limited choices and relatively high priced (compared to british standard, Shimano UN26 is $10). Only two swiss bb choices right now are IRD (~$50 complete) and Phil Wood (~$125 to ~$150 complete). Of course, if your bb is good, just service it and continue to ride. It could last you another 10 years, by then, there may be more choices out there.