409 or 348???

I got a big block chevy off of this guy who told me it was a 409, but I dont know for sure if it is. Whats the easiest way to tell if its either a 409 or a 348? I would like to know cause I am planning on selling it to anyone around alabama that is willing to pick it up.

Check out this site for casting numbers. I know that dip stick location (pass or drivers) will tell you but I can't remember which is which.

http://www.mortec.com/wmotor.htm