Baja Doodlebug DB30s serial number

I thought I knew the answer to my question, but was wrong. Where is the serial number located on a DB30S frame ???? Here is thanking you in advance !!
Thanks Chipper !! That is where I thought...or knew. I called the person that bought the bike for the number and told him that, but he said it wasn't there. I'll just ride over tomorrow and get it. I need to order his some parts. Thanks !!!