[classical glass]

Hi guys, I'm trying to register my cobra the paperwork going to the state is asking for the engine serial number. I found the casted date code (Sept 8 1966) and it's definitely a side oiler. I looked on the right hand front side of the block and there is absolutely nothing there. I looked above the starter motor and ounce again nothing. Can anyone point me in the right direction to locate this info? The state won't accept my request without this bit of information.
Thank you in advance.