bolt threads all metric?

I checked online and found it will take a metal gasket when I put it back on. it didn't say what size nuts I'll need.

d there be a gasket between the sensor and exhaust when I put it back on?

ase the threads. I also tried the SAE dies, but they wouldn't work.

sounds like my neighbors truck when he drives by.

on. it didn't say what size nuts I'll need.

Dan, I just crawled under my truck and looked at my O2 sensor. The studs aren't long enough to have extra threads for me to check the pitch but the nuts are those exhaust capture nuts with the slits on the backside that Toy ota typically uses on exhaust systems. My guess is if yours fell out it is because those anti-vibration capture nuts were not used the last time. If I were you I would just get a set from the Toyota dealer, grease up the st uds with some anti-seize compound and put it back together with a new gaske t.