2011 QX56: Transmission trouble. Possible to replace (or repair) it myself?

[CueExFiftySix]

My 2011 QX56 had the engine replaced at 60k miles for the well known timing chain issue. (I'm the original poster in the huge and now infamous thread here about the issue) Now at 120k miles the transmission is gear hunting and struggling at low to moderate speeds on gentle acceleration. Dealership said it was the catalytic converters, so i had both replaced at a cost of around $4.5k. Didn't fix it. They have now confirmed the transmission needs replaced. Cost is extreme. Is this something I could possibly do myself? I remember seeing a thread on here a few years ago from a member who replaced his own QX56 transmission, but I can't find the thread now.

I also can't find a source for buying a new transmission for the 2011 QX56.

I also have a newer QX80. I would like to get the 2011 QX56 into tip-top shape to give to my soon to be 16 year old child as their vehicle. Not sure the vehicle is worth sinking the money into, to get the transmission fixed though. It still looks very good and seems very nice and solid, with the exception of the gear shifting problem on acceleration. Yes it has 120k miles on it, but only 60k of those are on the replacement engine.

So my questions are:

1. Is it wise to spend the money to have the dealership replace the transmission? (They quoted $7,500 but this was 1 year ago, after the catalytic converters repair did not fix it. I have no idea what they will want to charge now to replace the transmission)
2. Is it possible to source the new transmission for considerably less money and replace it myself? I'm no mechanic but I can figure things out and follow instructions, and I have plenty of tools.
3. Is it likely the transmission will fail completely sooner rather than later, or can they keep going for years with the problem I've described?

Thanks for any guidance you all can provide. I'd like to make a smart decision that puts my child in a nice, solid and safe first vehicle while keeping the cost reasonable but also not sinking money into a sinking ship, if that is what I have.

 

[marctronixx]

1. if car was maintained properly -- yes
2. doubtful
3. which tranny? the one now or a rebuilt one? if the former, we, on the internet, don't know the history of the tranny so its speculation at best. a rebuilt one should be fine.

the qx is a solid vehicle, it has a long history of pleased owners.

cant see your car but if its been kept in good condition and maintained properly as per manufacturer direction, the car should last for another 150K or more. there's people with 300K armadas that had zero issues and i suspect there are many happy qx owners.

most people who post on forums are the ones looking for answers. rarely do you se random owners posting up how great their car is.

 

[primov8]

Hate to say it, but the dealership lied to you about the catalytic converters being the problem. When a catalytic converter(s) begin to show signs of deterioration, certain DTCs start popping up which is diagnosed by looking at specific fuel trims, O2 voltage, etc.
Has the ATF ever been changed on the transmission? This would be the first thing I'd do if it wasn't before going out and spending $$$$ for another transmission.