"That is not always an easy ta
"That is not always an easy task. The Distributors place their orders for the 2GM20F and when complete the Yanmar factory will build exactly that amount. They will not make surplus. The Distributors will get the order in batches ie from low to higher s/n's. You can call your local distributor and ask. If that s/n does not show it will be close to that s/n batch they have and they can ball park you a date. If the engine was sold into the boat when new then that local Distributor would have that record. Yanmar do not bother or devulge that information. You will not know that commission date to end user. Then it depends on how well that Distriburor keeps s/n records... Good luck, Ron"