battery cable frutration...

So I just went to napa to get a battery cable for my 71 dart swinger 225 and did not have a good experience. I figured the cable I need would be available over the counter, but no such luck. They had no idea what the connector was on the positive cable (which I figured was just a stock connector right?). They said they could not order anything like it.

Then on the new universal negative cable the stock bolt I have to attach to the engine is too big to attach the new cable to the engine.

Can't I just buy the same cables I'm replacing or do I have to do some splicing no matter what? I've attached a photo of the connector in question on the positive cable.

Thanks - yes, I'm a noob...so thanks for your help.

(just noticed the subject of this thread says "frutration"...sounds like a new word, but really meant to say FRUSTRATION!)

batterycable.jpg