Adaptor for trailer electrical connection?

Greetings:
 
I own a 2003 Expedition E/B Edition. Recently, I purchased a folding 4 X 8 trailer from Northern Tool, which includes a basic light kit. Problem: the 4 prong connector with the kit "sort of" resembles the factory installed connector next to the hitch. But they don't mate due to the rubber housings being slightly different shapes (one is rectangular, the other having rounded edges). Does Ford (or aftermarket auto parts stores) make some sort of adaptor to enable the connection?
 
Thanks for your help.

just go to wal-mart get a trailer wireing connertor kit if one end of that fits u'r expedition cut the end off the traile splice the end that fits onto trailer or u could cut the one on vehicle but i would rathe cut the one on trailer and the wires are color coded

And if you are not a Walmart fan or don't have one around, the autparts stores will have something that should work. 

I appreciate the replies. I'll hit the neighborhood parts store and then WM if that doesn't work.
 
Thanks.