M 1.0t Mono Switch

I have two M 1.0t Magnetic field amps and have a question about them. Do any of you know if there were different models made or if they date they were made makes a difference whether or not there is a bridgeable mono switch on the back?

The reason I ask is one of the amps I own has the bridgeable mono (bridgeable to 1000 watts) switch and the other does not. Any info you may have would be appreciated.

yep, early ones did not, later ones did....

I have two M 1.0t Magnetic field amps and have a question about them. Do any of you know if there were different models made or if they date they were made makes a difference whether or not there is a bridgeable mono switch on the back?

The reason I ask is one of the amps I own has the bridgeable mono (bridgeable to 1000 watts) switch and the other does not. Any info you may have would be appreciated.