I contacted the company CSY & Son, responsible for Yaesu spare parts in Italy. Currently, only the PA board CB1152005 is available, which is compatible with all 817-818 models.
They told me that the one I purchased is the last one they have, but they expect more to arrive from Japan.
They could not tell me how long the parts for these radios will be available, but for now, there are no issues. It is possible that the situation may change in the near future.
A sore point is the price. The PA board costs 146.40 Euros in Italy.
