Grover67

Its stil going to be pretty tight getting a hose down into the bottom. The vid Z45 posted is pretty much what you're up against. Live I mentioned before about if you do it on a lift it'll be a little easier to work around than doing it off the floor, and yes it would be better to clean it out fully. It will also depend on how many miles you have on it and how much you've used 4WD. Mine was pretty clean when I changed it around 30k

Front cover takes some work to get off and you'll need a gasket as its not reusable, if you have it on a lift it'll help. Just hope most all of the gasket comes off with the cover as its not the easiest to scrape off, not sure what was used when they installed it.

Winter blend gas will show a little less mpg also

https://greendieselengineering.com/product/gm-1500-lm2-duramax-engine-trans-hot-tune/

Have they been all OEM's brakes you are going through??

I did the PPE trans oil cooler first. It held the trans temp down some but its being regulated by the bypass. I changed out the bypass with the PPE and it runs about 40-50f cooler overall winter/summer. Just got back from doing some work today at our cottage about 2hrs away. Mostly highway running 80mph, it was 80f out today and once the trans temp stabilized it runs right around 158f. Winter driving here in Michigan it runs a little cooler to a little warmer due the radiator louvers shutting/ regulating. I would just run the bypass and if needed add in the cooler.

It wasn't 100k on the LM2's, the new ones with the same belt are 200k I wouldn't even be concerned at that point.... https://www.youtube.com/watch?v=Ea5r6XAK3bk

Are using the recirculation button or is it drawing air from the outside? What is the center vent temperature coming out when on max cooling while driving? How were you reading or doing with your 45ish pressure reading and what made you think you needed to add refrigerant?

Supply issues are still a issue hard to imagine that it is... I went with new rotors and pads(aftermarket) all the way around @ 30k. Pad life was showing 88/90% and they had alot of pad left but I was getting vibration issues from the pad material imbedding on the backside of the rotors, due to what pad material gm has to use anymore.

Ya ran into the same issue when I replaced mine and couldn't reset the life monitor. Checked with a couple of local shops but they had no clue. So bit the bullet and checked with the local dealer and they got right in and reset it. They say GM does it as a safety issue and only wants dealerships to reset it.....crap

A good accurate digital thermometer and check vent temperatures to see difference, they'll be some but shouldn't be a big swing.

Yes you are correct and depending what truck you have there are different gaskets -grover67

Thought about trying a bypass to see or you just going to let the GM network do its thing? Its a easy swap.

Sounds like the bypass could be hanging up and not allowing it to open to allow fluid to go to cooler coil.

How many miles on it? Was yours using oil? Did you take off the inner cooler and clean it out and if you did how much oil did you find? thank you