It's best to replace it with the same part if you can find it and the price is not too obscene. I would expect quite a few similarly rated parts to work, but sometimes rely on specific characteristics of the original part and may not perform well with a sub. Using an exact replacement greatly simplifies the diagnostic process. If you install a sub and it blows up, was it because the sub was not suitable, or do further problems exist? It isn't always easy to tell.