Marantz 240 amp

Question for the group. I am considering purchase of a Marantz 240 amp with the serial number prefix 240b-and number 3317 (240b-3317)  I haven t been able to find any information on the number other than none of the ones I saw had the 250b-xxxx. 
The other thing is the front plate appears to have a etched brushed label, rather than on the face.
I am wondering if anyone could shed some light on this mystery?
Scott