At first I thought the same thing, but after talking with a teck guy from Wells he informed me that this product is made by Wells and sold to Autozone and Airtech under the Wells name, for resale to the public. Timbo TPS is made by Williams, he and others, add the harness because the Williams unit is not a direct fit for our trucks. The Wells unit is design specific for our trucks and is a direct replacement. Both Wells and Williams seem like reputable company's that have been making automotive products for many years.
The Wells unit has only been on the market for a few years but seems like a better design as there are no moving parts to wear out. Wells other improvement to there TPS over the Williams and the factory models is that they designed a circuit board that can stand up better to the vibrations and the heat from the Cummins engine, vibration and heat has been proven to shorten the life of other units.
Wells has a video on utube that is worth watching