Negative SkyBound!! My mistake and apologies. The 1000 and 1200lbs heads share the same thickness steel. But the square sockets the spring arms go into are different sizes. 1000lb is 1-3/8" square, 1200lb and 1400lb are 1-1/2" square.
From the research I did, if you need a heavier Equalizer load distributing hitch, Sell yours and buy another whole new one. They have designed them so you can't buy larger spring arms for smaller hitch. The 1200lb and 1400lb are the exception, as they are the same arms anyway with different part numbers on them.
My advise, if you need a 1200lb Equalizer 4 point sway control hitch. You may as well get the 1400lb. Same spring arms just heavier head to handle larger tongue weight. Better to be on safe side and if you a get bigger trailer later, you have a hitch to handle it. The only disadvantage is the 1400 weights a bit more than the 1200.