If the old generator has a different ear than the new one, the new generator probably is not for your car. The ears are primarily what dictates the application or the generator.
If the old generator mounted to your car, the bracket was mounted correctly. You could have the bracket modified.
Your best choices are;
-Return the generator and get the correct one.
-Find a correct generator and salvage the bracket, it probably swap out on the generator you bought, or when you find a generator, take it to a rebuilder and have it fixed.