It passed, finally. To recap. Just after my last smog (every 2 years) my CEL came on. I tested and the driver's side forward cat wasn't working (the outlet temp should be higher then the inlet). As I had just passed I did what was right, I shut off the post-cat O2 sensors. Roll forward 2 years. I spend the entire summer building a deck (that still isn't done), and I must fix the Hummer by Sept. 18. Yes, I know, it's October 27 now. But I jumped forward. I ordered new cats when the lights came on - but universal, Magna flow cats because at that time replacement cats weren't available. Now they are.... $450/side. You need 2. Not just that but you would have to pull the entire exhaust and likely the t-case to get it in. So I cut. and put it back together however, I had a problem - one of the bolts didn't come out of the exhaust manifold. I had to pull the manifold. I put new studs in place and the flange didn't seal.... long story short, the studs that I got from NAPA have a shoulder that kept the flange from sealing. Then the O2 sensors went out (the 2nd ones). Then the threads (which were, admittedly, marginal) on the passenger-side primary O2 sensor let loose. I fixed it with a hose clamp. it works. Judge if you will but by now I'd have to pull the exhaust to re-weld a new bung in place - which means trying to not get another leak.
Surrounding all of this is each time I had to disconnect the battery, it would take a solid week before the sensors would all come back online. When the 02 blew out, it was ready, finally, to test again.
I did change the spark plugs, and that caused its own issue with defective plugs and a cracked (only on one side) ceramic housing - and those blew several coils before I phoned a friend and got help.
Then the transfer case went. For about 6 months I'd get a weird, impossible-to-repeat, noise from either the front right or rear right. I pulled the differential cover to see what's what.... no joy. Then the chain went through the side of the case.... found it! A warning, if that noise is happening - I didn't know and this is my second case, and likely the second time it's happened to me.. I thought I blew the first because of something else - the idler can loosen in the transfer case. Then it starts catching the chain. My idler in this case is wadded up - it should be flat. Fortunately between the 2 cases I had, I was one new chain away from a solution....
In all of this I also replaced the radiator - the CVS all-aluminum radiator didn't last 2 years before it started leaking
Did I mention the starter also is starting to not engage? I've not changed it yet, but will very soon, but yes, in all of this that started happening.
But I have my Hummer back and I am happy. Cars break, schmidt happens, usually all at once.... but it's fixed. I know it seems cursed, but sometimes things go that way - yes, I cussed, a lot, perhaps even yelled at God for a bit... I even drove a couple diesel Colorado pickups .... but it's fixed. Probably will sell it in the next year or two, or maybe the FJ40 will go instead and I'll take this to the Duramax concept I had before (well, maybe mini-duramax from the Colorado - those are cool and drive really well)
It also has more power and about 10% better fuel economy, more like 20-30% on the highway.... when I did the cats, I eliminated the rear cats - they aren't tested so they aren't necessary. What I will do next is remove the resonator and put a regular muffler in place of the magnaflow that is on there now.... I think it's a bit buzzy as it is now.
I think that's all.... for now.
*edits*
yes, I did save what was left of the case, I have a forward half of a case, and the planetaries. When the case went the first time, you couldn't get a new chain - GM had stopped producing them, and the aftermarket wasn't yet producing them. I also needed a gear - praise because this time didn't take out the gear that I needed (and is still impossible to get).... point is, if anyone needs bits, I still have some.... I may do a parts post in the near future because I'm getting buried in parts I'll never use.