This seems to be asked quite often, so I decided to do some extensive research into the subject. The wiring harness is a perfect example of you get what you pay for. Here are just a FEW of differences with the Year One harnesses. Some are visual others are not.
The wire used in Year One harnesses is crosslink polyethylene rated at 125 degree C (257 degree Fahrenheit), other manufactures harnesses are rated at either 85c or 105C (185/221 Fahrenheit) or a mixture of both. The crosslink polyethylene is non combustible and stays flexible and in theory any device that shorts out will only take out that circuit and not the entire harness.
All hard shell connection systems are molded out of Nylon 6.6 instead of polypropylene, the benefits are higher temp rating, better elasticity and chemical and ozone reflective properties.
All terminal crimps are done to pass industry standard pull tests. In addition terminals are the original manufactures or duplicated to the originals, they are not some modified terminal made to fit.
All molded connection systems are molded out of a high temp rated flexible material, rather than the less expensive PCV that hardens after a few years.
Solder is leadless thus environmentally friendly.
Complete harnesses only are built. If there is a huge differential in the price of the harnesses ask questions.
Electronic conversion harnesses are built to performance standards as to wire length and resistance standards. This means that the ECU’s must be placed on the firewall, where Chrysler designed them to be. Extended length wire affect resistance thereby affecting the performance of the ECU’s.
Below are some differences in connectors.