If this is unique to you (meaning others are not reporting the same crack), I’m wondering if the passenger side is stressing/stretching the elbow due to movement of the other sections being further apart from normal.
The more I look for info (albeit not dedicated investigation), I see people say the crack failed at a weld. I'm not convinced mine did, but maybe, then the spiraling crack around the tube ...
These engines (same mani design) were in hundos/LXs, 470s, sequoias and tundies.
hundy/LX folks here on mud mention this failuer and of course GX folks. Not much pops up in the Googs besides mud and club lexus stuff, but i'm not looking too deeply either...
some fix with weld, others replace, others DT headers.
this is a good
reaffirming read (I'm now a month in with no expected delivery time on the horizon and wifey poking me for having a reliable vehicle for winter trips, upcoming spring and spring break potential not to mention her longing for a good summer vacation)... Anyhoo, part of this updating jibber-jabber post is because I'm contemplating options.
Please PLEASE don't flame me on this

, I've already beat myself up about it because but for the love ... , i can't find the old manifold!!!! EFF!!!! i was thinking i'd weld it up and patch it then reinstall it to kick the can down the road
(effing eff, i think i may have tossed it away). So, I'm sorry to say so but sadly its true, I don't have he old mani to repair and install as a temp fix.
Anyhoo, I'm thinking I'd rather weld up
flanges to the DT headers than weld the cat to the headers. With flanges I could match stainless steel to SS vs welding the SS headers to the steal cat tubing (cold rolled I assume), AND not recreate the awkward off-kilter weighted design flaw issue of the stock mani.
To
@ArBrnSnpr and
@Rednexus are your headers just tacked on the outside (but full weld on the inside)? The ilinked review talks of good chamfer-finished welds on one side and kind of flat unfinished on the other (making a poor suface for exhaust gases to flow over when leaving the head).
I suppose I should do a search or maybe start a survey thread for exhaust manifold failures. I'm curious how common it is... I supposed with enough time it could be a 100% failure rate, but also maybe a reasonable time till failure is at play too (I think mine first cracked the sad in 2019 (so maybe just under 200k?

)
So... Does anyone know others with DT headers long or short? I'm interested in a larger sample size of experiences and maybe experience through time... I've heard early gen headers had cracking issues and I think v 1.0 wasn't stainless at first. i read a long thread about a dude who had a plain steel air-injection tube, when the header was stainless, and the injection tube rusted over. Eventually DT stepped in and replaced stuff, but there was plenty of forum banter and opinion in that thread for a while.