Where is Kawasaki Vulcan Classic engine number located?

Look into the space between the exhaust pipes on the right side of the bike at the rear of the engine. The engine number is stamped on the side of the engine block at the bottom. ('09 Vulcan 900 Classic LT)

On a 2000 1500 Vulcan Classic. It's stamped on the *left* side of the crankcase - on the kickstand side. It's between the frame and the crankcase so you need to view it from an angle; looking from the front. Wipe it clean first and and bring a flashlight...