What year is this engine with cast number 10066036?

The casting number 10066036 doesn't directly correspond to a specific year. Casting numbers are used to identify engine blocks, but the year of manufacture is not always directly encoded within the number itself. To determine the year, you need more information, such as:

* The make and model of the vehicle: This is crucial. Different manufacturers use different casting numbers, and even within a manufacturer, the same casting number could span multiple years.

* The engine type: Knowing whether it's a V8, V6, inline-4, etc., significantly narrows down the possibilities.

* Additional markings on the engine: There might be other numbers or codes stamped on the engine block or its components that indicate the year.

With that additional information, you could consult a vehicle identification number (VIN) decoder, a parts catalog for the specific vehicle, or an engine identification guide specific to the make and model.