Krell ksa 200

Hi everybody.
I have been offered a ksa 200 for a nice price on e-bay,the person sent me a couple of pictures of the item, the worries i have is that the serial# is missing.I ask this person of the #and he claims it to be a four digit serialnumber,but on my ksa150 its 7 digits serial,what do you think? Is it a fraud or not?