Brake Antilock Wheel Speed Sensor problems of the 2003 Nissan Frontier

I noticed a "ticking" sound from the rear of my truck. My own investigation I found that the "housing" that the rear speed sensor is mounted in is cracked. This is what controls the abs system for the rear wheels. The "housing" is mounted to the front of the differential. I did check and there is/was a recall on certain Nissan Frontier trucks during the 03 year. I was told that my truck is not covered under this recall. The part, which I have yet to replace, is extremely corroded for being only 6years old with 45000 miles. It is made of aluminum. I am having a hard time locating the correct part, even from the dealer. The part that I was told is the correct one is $232. But doing a little research that part is only the wiring for the sensor not the metal "housing". I noticed this about 2 months back, but thought it might be some rust in the brake drum from the winter.