The 7-pin will give you more options, but you'll need to run wires to the front of the Jeep to support it. The 4-wire can hook right into the tail light. You can can a 7-pin to 4-pin adapter in case you need to plug in a 4-pin trailer, so the 7 pin is more versatile. Having said that, I went w/the 4-pin as I mostly use the hitch for bike and cargo racks. I'd really suggest just doing the hookup yourself, it's trivial.
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