Have to replace #3 sensor,if threads strip in the exhaustpipe is there any way to repair the threads.would a heli coil work ?
What does a new Y pipe cost ??

 

Long before I would suggest replacing the y-pipe, I would have a new O2 sensor bung welded on. Should be reasonably priced at a true exhaust shop (i.e. not midas or monroe). Try to find a mom/pop exhaust shop in your area and take it to them. They should be able to cut off the existing bung and weld on a new one.

Helicoil may work, but price the new bung.