It is hard to tell without seeing what you have. I just ordered the same battery. If the polarity were backwards and you cannot change it, I'd cut the cables and reverse them. Or I'd use one that I have from another battery pack. I've also seen threads where Rat Shack sells the cable that allows you to (buy and) put any size pin, at either polarity on either end. It was only a few dollars for the whole thing.
Added: March 6.
I just got mine in the mail. It is idententical to the Wal Mart battery that came when i purchased my UA -5, except for the label, and the cable.
I see what you mean, that the jacks are not reversible. I would do exactly as stated above IF the polarity is wrong. Have you tried it yet?