I should also point out here that GM uses more than one 10-speed automatic transmission.

The Ford-partnered 10L80 which is used in the SUV's and light duty trucks, and an "Allison" 10L100 for the heavy duty models. (I use the term in quotes because I don't know the extent of Allison's involvement. Maybe GM just built them to a higher spec, and then paid Allison so they could stick an emblem on it). It seems the 10L100 may have some issues: https://www.mylemon.com/lemon-law-blog/gm-10-speed-transmission-problems-what-you-need-to-do-now/

There's also one for the Camaros & Cadillacs (10L90)

Posted by: @baloney

Are the i6 duramax diesel engine and the 10-speed transmission reliable

no and no.

Posted by: @baloney

fuel efficiency is also important to me

buy a Prius

I didn’t think the trail boss came with the 3.0 diesel.  Maybe I’m wrong.

Right up front, I’ll disclose that I bought one (2022 Sierra Limited SLT 4wd) this year.  I am not a GM/Chevy/GMC fan boy, to say the least.  My last pickup was a 2014 Tundra.  I would have bought another Tundra had they kept the V8, but they didn’t and the turbo-6 is having some teething issues (and real world economy is not very good).  I looked seriously at all the half-tons except the Nissan, and decided that the 3.0 Sierra was the pick of the litter for my usage.  7500 miles so far, admittedly not a lot, without a problem.  30 mpg highway, 26 mpg commuting, 17+ mpg towing.

Anyway, basically yeah, it’s a solid power train.  So far.  If I recall, the baby Duramax just came out in 2019 (or ‘20), so there are not a lot of high mileage units in circulation outside of GM’s test fleet.

First let me talk about the transmission. The 10-speed was jointly developed with Ford.  It seems not to have any major flaws, and GM seems to have the tuning dialed in better.  Shifts are smooth and drama free.  DO NOT, under any circumstances get a truck with the 8-speed; totally different transmission and it is a disaster.

But the motor is the killer app.  It is exactly as advertised: smooth, quiet, no lag, and efficient as I said above (easily beats EPA if you don’t drive like a maniac).   I know about the oil pump belt and I don’t care.  It’s a $1000 charge once in the life of the engine; less than a set of tires.  The no-start issue is the real gremlin you have to worry about, but it is very rare.  And since the GM warranty now goes to 100000 miles, it shouldn’t be a deal breaker.

My eyes are wide open about 1) GM quality, and 2) government emissions nonsense.  But I figure that with the fuel savings I can afford a repair or 2 when it goes off warranty.  Overall I think I made the right decision. 

Do your own due-diligence.  But, yeah, I think it’s a good truck.

Recently I am considering the 2023 diesel Silverado 1500. Especially the trail boss trim level. 

Any thoughts on this truck?

Other than it being overpriced for what it is (IMO),

Unlike the old DuraMax V8 built together with Isuzu, these ones were developed by German Opel in Italy.

(So it's an engine based of 1.5L 3cyl, and 2.0L 4cyl high-tech German-Italian units. doesn't sound promising.)

As it seems this LM2 engine was first used in 2018/2019 and is already getting replaced next year - sounds bad...

The same happened with Opel's smaller versions, they immediately replaced it.

(ironically, the engines Opel replaced it with are made by Ford)

Both of its creators just got rid of it, after only 4 years. (after spending a around billion dollars on R&D)

This does not sound good at all! If you're planing on keeping the car for a while, I'd avoid it!

the 10-speed transmission reliable? (...) torquey Diesel engines

So far I've herd a lot of negative things about them,

and I can only assume that with more torque (and the 3.0L is very torquey) there will be a lot more wear.

I drive about 60 miles each day to work

Well for $53k you can buy pretty much almost any regular car -

if you want efficiency you can get a top of the line Camry Hybrid, if you still need some towing ability, the RAV4 hybrid can tow a bit.

But if you want the best possible efficiency, the Prius HEV/PHEV is a solid choice - and partially sacrificing reliability and longevity for better practicality and even better efficiency a Niro HEV/PHEV, both of these can get over 50mpg.

But for now I'd avoid these high-tech diesels - I haven't seen a diesel made after 2018 that doesn't have issues.