if your Durango doesn't have the factory tow package, which would already include the pre-wiring for a brake controller and 7-pin wiring harness, then the Durango DOESN'T have the factory tow package, therefore doesn't have the 6200lbs. towing capacity.
plus the tow package also includes a trans cooler and a good towing rear end ratio, which yours may not have.
your Durango will have much less towing capacity unless you exactly duplicate the factory package.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC