Casting number

I do not know anything about casting numbers, my bad. I am looking at a 360 with the following cast #, 4006830-360-2. I know it tells me it is a 360 but what else does it indicate? I assume it tells the year. But I don't know? Any help would be appreciated. They want 500 for it complete. Just found it on, CL in Florida. Waiting for a reply on the miles. It says it is a 78 with about 400 hp.