knock sensor

Does anyone know how hard it is to install a knock sensor in a 2001 nissan quest and where it is located

is a big job, you have to take 1/2 the engine apart just to change the sensor which is in the middle some where in the engine. I had it done for my van..it took a few hours and a nice connection that did it for me for a good price. but if you dont have a good connection meaning friend or some one that does side work, then you are looking at a pricy job.. ps is not the price of the sensor or the parts its the job it self thats pricy and not every one wants to do