If customer already issue PO, then it is better for you to send YASC PO and advice you leadtime accordingly.
If urgent and no stock, then is better for you to straight away send us Critical Order for Large Engine, ECHO Order for Small & Medium engine to get best possible leadtime from factory.
Back and support with Order is always more powerful than inquiry and get best possible leadtime for Order than Inquiry.
Perhaps you may want to share with us the background reason for you to send inquiry instead of order since you already have order in hand.