McIntosh MC250 service manual for serial number 13L04 or 18L04

I've downloaded a number of PDF versions, but none relate to the particular unit I have on my bench now.
I need to identify some parts that have proprietary p/n on them.
The serial number is partly defaced, so my best guesses are in the title of this thread.
Can anyone identify this amplifier and the correct schematic and parts list?