First off - sorry for not providing pics - I was in "get it done" mode. It's very unlike me.

After several months of dealing with a cracked drivers side eBay header - I finally pulled it and welded the cracks. I MIG'd the header using non-stainless wire. I had the stainless wire, but I'm so fed up with the horrible leak - I didn't even care. Ya, I know it'll rust - still don't care.
Under the header wrap I found two tubes cracked along the collector. The shortest tube and his neighbor were the culprits. Both tubes had cracks running at least 50% around.

I think the header wrap is to blame here. Below it I discovered black, almost burnt looking pipes. The wrap was extremely brittle and disintegrated into a powder as I cut it away. I'm pretty sure the wrap kept the heat trapped in the headers, not allowing it to disipate quick enough. I know many people run these headers without issues - in even harsher conditions than I. So, I'm calling out the wrap.

I replaced the header and sealed it to the head using RTV Ultra Copper. No gasket. I've had good results with this method in the past. I allowed the RTV a full 24+ hours to cure before driving the truck. Today is day one - so far so good. And I can say - driving a truck that doesn't "TICKK THICKK TICKK THICKK THICKK THICKK THICKK...." is quite a treat.

Needless to say, I didn't re-wrap the header. I guess I'll see how long it'll last.

 

Get some VHT ceramic header paint and paint the headers. It will help the heat transfer (into surrounding areas) a little and help keep the steel MIG wire from rusting.

 

FWIW, I welded in my Ebay Y-Pipe with standard MIG wire, and it's held up well for over a year now, WITH some high heat paint on it.

 

Damn, I really wish I thought of painting the header while it was out.
Or posted about the job before I did it - then I could've acted on your suggestions. I'll just have to get in there and make it happen.

Thanks for the good ideas!

EDIT:
Day two - so far so good! I really want to put some weight behind it and go run down the highway to build some heat. But that'll have to wait for another day.

 

Interesting to hear about your issues. My headers are still pretty decent, even shiny for the most part. I haven't towed heavy with it whatsoever although I have had it idling/running-slow in 90+ degree heat for 4-5 hours at a time.

I was on the fence about wrapping my headers when I put them in. In a way, I'm glad I didn't. The only thing I wish I did was put dynamat on the firewall

 

I really think the wrap is what did mine in. I think the tubes are a bit thin and just can't handle the heat when wrapped. Of course, the wrap proved to be EXTREMELY effective as a sound barrier. Now that I've removed the wrap I can hear the "header flutter" quite clearly. That tinny sound that's cool in a big block Chevelle - but not so much in my Lariat SD.

The winter months made my "not that bad" leak - very bad. Plowing 3 feet of wet snow all day, all night without shutting the truck off for 30 hours is enough to drive some temps up in those headers.

 

My ebay headers turned black and crusty in about a week.