I'm wondering if the new ecm is learning.
Are you saying you didn't have throttle lag before the repairs or that the throttle lag is way worse?
How many miles have you put on the truck since the NOX high code?
Do you think using a clear silicone grease would keep the gearbox grease from hardening/gumming up again?
While you were in that deep, did you "service" the other 2 gearboxes?
No experience with the deck system, but I would wait and see what the difference in height is.
Nothing wrong with a little sag. Will ride better and be a bit more level. Unless you did a level kit on the front already.
It's not my money, but I would suggest bags over blocks.
No I have not.
They (gm) did some "improvements" for the '24's. Maybe the 'improvements" weren't!
Are you saying your Dad's dealer has 500 of them down, or gm customers, nationwide?
You could also have them look at Bulletin 22-NA-027 and see if your camshaft cover serial number falls into a bad design.
See attached bulletin. You could inspect it yourself.