Missing cat flange bolts

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ukrkoz

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OK, now I have serious issue.
My 07 Tahoe had engine out and then reinstalled back.
Done by shop.
Ever since, I noticed that, when I stop and idle, I smell exhaust inside. Knowing that it does not have cabin filter, I wrote it off on stinkers around me in the traffic.
Today I did Chris Fix's exhaust leak test and found that there significant leak from cat area.
Got truck up on the ramps, rolled under and found that cat to exhaust manifold junction is missing one bolt on both sides. Of course, it's the ones that are right against the body side, so I can't even get my fingers there. On the driver side, it looks like it's a through hole and all there's to it is to drop bolt in and tighten nut on it. Can't tell on the pass side, can't tell. Not sure, maybe it's just a stud, ripped out on the driver side.
It looks like that can be accessed from the top and bottom with very long extensions. Hands simply don't fit there, it's narrow gap and driveshaft on the driver side, covering it.
I have zero hope I'll get it straightened through that shop (took truck back about 2 months ag and, honestly, I don't want them to touch any of my cars again)

Quite desperately asking - is there DIY way to reinstall those bolts WITHOUT dropping both exhaust pipes? Are those bolts or studs? If studs, then I'll have to drill it out on the pass side, so I'll have to drop exhaust as there's no way to drill through otherwise.
I have lift, I can get to it from the bottom and rig some extensions. It's getting it from the top... and my son, who could have helped me, separated his AC joint a week ago and is decommissioned as helper.

I'd really prefer not to drop exhaust... I had to do it on 99 Silverado, that was absolute PITA.
 
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ukrkoz

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OK, so it's studs, not bolts, and I'll have to drill out the broken stud base on the pass side.
F....rs...
Anyhow. Found this vid here:


But it's for RWD model and mine is AWD model. Does it make any difference? There's transfer case to differential driveshaft on mine, now present in the video.
Damm it...
 

swathdiver

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Right, studs and nuts and two kinds of gaskets, different on each side. Frankly, it's easier to drop the Y-Pipe and fix the mess than try and contort yourself to do it another way.
 
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ukrkoz

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Yeah, I figured that much. Does not look like much of hassle having it up on the lift.. Maybe I can get away with just dropping Y-pipe enough to clear access to the bolts... Don't really need to remove it completely. As far as I can slide bolt from the top on the driver side through the flange and drill hole for the bolt on the stud side... Maybe even tap the hole for bolt there. That'd have been the easiest to do.
 

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