2000 T4R upstream O2 sensor hold down nut size?

[Kennysmoke]

I just bought a 2000 SR5 Sport on Friday. While driving it back all of a sudden while going uphill the truck exhaust got real loud. I crawled under the truck to find the O2 sensor on the cat just hanging from the wire. After close inspecting it appears the last time the sensor was changed the hold down nuts were never put on. It looks like rtv sealant was the only thing holding it in place. It happened right across the street from a NAPA store and after trying several different nuts none seemed to fit so I just wrapped it in tie wire to get it home. The threads on the studs are in great shape almost zero rust and just couldn't get the nuts to thread on. I didn't want to cross thread them so opted for the wire to hold it in place till I can figure out the correct size. Does anyone have any idea what size and thread the hold down nuts are? Thanks in advance.

 

[m0ist]

I believe they should be m8x1.25. Are your studs still there?

 

[TheDurk]

I believe they should be m8x1.25. Are your studs still there?

This is correct. The originals are stainless steel.

 

[Kennysmoke]

I finally got around to buying the nuts and o2 gasket for the upstream sensor, I don't know if I've got an aftermarket cat or something but 8x 1.25 nuts will not thread on. Studs are in very good shape. the nut barely gets started and stops as soon as the whole thickness of the nut gets below the tapered tip of the stud. I guess it's back to the tie wire until I can get this shit figured out....