the sensor was removed from the back and plugged and the old one put in the front the tube from the side was also added, this was the most expensive part as it was pressed in and tapered at the bottom so it had to be exact, the shop that did this builds NASCAR heads so I was not afraid but the small tube could be easily damaged, the shop that did this also had the capability to build it from scratch if it was botched. All in all it cost around $400. but much of this could be done at home if you have the time and tools and will. I had it done because my work is running non stop overtime and the temp in my unheated garage is still in the 20s and 30s this last week. We will get a warm up soon and I will put this back on and start adding all the motor parts I have accumulated this winter