1650RD-CAL what does "CAL" mean?

I have a number of 112 RD 50 amps. All list the chassis as 1650RD except for one. The one says 1650RD-CAL. It sounds a little different than the others and a repair man once told me it was different than the others.
My Question - What does the "CAL" designate, what does it mean?

Can't answer THAT one. Hope somebody else pops in to help

The difference is in the ground switch capacitor. The standard US (i.e. Domestic) version uses a .047uF cap, the 'CAL' (California?) and 'CAN' (Canada) version uses a .010uF cap. Different safety regulations require different versions even within North America. I respectfully suggest that the sound difference you hear is not because of this capacitor (unless we are dealing with really bad mains hum).
-Lars Mikael (in Canada)

Thanks for the answer. If anyone else has any additional info, I am still interested. Obviously the difference in sound could just be the individual amps. I have a number of blackface twins and they all sound a little different.
The one with "CAL" sounds a little cleaner and a little brighter and more sparkle than the others. I am able to turn it up a little bit higher. I normally play it on about "6" to "7" on the volume with bright switch on, treble on "9" bass on "4" gain on "6.8" and reverb on "2.5" (not that any of the settings make any difference from amp to amp or person to person)

does all this mean that this amp should have never left the state of california?

Ever try switching the speakers amp to amp to see if the bright, clean sparkle follows the amp or the speaker? that could be the reason. Or ask the repair man, next time she's in for a tune up, what the difference is. just some thoughts
Dan

Yes, I should have asked the repair man why he thought that one was the "good" one and was different than the others. Yes, I know it is not the speakers. I do like them all, just this one more than the others because it has more clarity. All have the stock speaker which I like in these amps. My usual preference in speakers in the 60's era JBL Alnico that you would find in a Blackface Twin. I have a stockpile of those old JBLs but in the MM amps I prefer the stock speaker. This particular MM has about 600 gig on it in the last three years.(not that it matters)