I want to remove my rear O2s and but bolts in there place but i don't know the size?

 

I wanted to do the same thing but never did find out the size. I simply went to the GM parts counter and bought the plugs they make for this purpose. There's one plug that fits many GM vehicle applications as it is a standard thread, I don't have the part number sorry <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />

 

It's 18 mm thread like the larger spark plug thread size. If you had too you can use a old plug to plug the hole.

 

I was just looking through LPE stuff on their website and came across some stainless plugs they sell for this. Part # LN0055P and they're $4.95 each.

 

Have we ever heard of a vernier caliper and a thread pitch gauge class? I guess not. Preferrably one in metric units

 

I just went to NAPA and got some 18mm ford spark plugs and screwed them in. Works perfect and gets a ton of looks when ever someone is underneathe the car. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Eric

 

Yep, 18mm * 1.5

I had to find a tap for a weld-on bung that, UHHHH...got a little hot welding it on. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

I think Thunder Racing sells plugs for the bungs. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

John

 

If you go to any bolt supply company that sells hardware typically they will have a stubbly 18x1.5mm oil pan bolt with a plastic washer on it. This is what I used (ditched the plastic washers of course!).