i have a 2009 dodge durango 4x4 with a 4.7l. brand new motor made it 60 miles down the road and it started knocking. i pulled motor and all spark plugs and as i was turning the motor over by hand it keeps trying to bind up in the same spot ever revolution. and on the bottom of one of the pistons looks cracked.

 

This is the Dakota section. You need the Durango section.