[Boatanchors] SX-28 Question

[Richard W. Solomon]

Looking in the SX-28 Manual it says the AC On-Off Switch is located on the Tone Control.
Not in my SX-28. It is on the AF Control. The Front Panel has AC On engraved by the 
ToneControl but the Tone Switch looks like original equipment.
Everything I can find says it's an SX-28 (round coil forms, not square, etc). 
Maybe I have an offshoot that was done between the SX-28 and the SX-28A ?? 

Any ideas ? 

73, Dick, W1KSZ