Got my estimate from the dealer. Technically the EGR cooler isnt known to have failed but its at the time and mileage that it would be dumb not to replace it now, because a related tube/hose is what's leaking coolant and it needs removed to replace it.
IOW its the day cab all over again as I suspected.
It also needs a couple sensors. One for the oil temp and one for the soot. Those were my check engine light.
And it had some stored codes for erratic voltage from my batteries being poor (according to the dealer). I knew they were getting poor, I was just hoping to get closer to winter before replacing them.
Anyway its looking like I'll be in it for a little over $8,000 and it should be done next week.
Salty but if it sets me up for more uptime in 2027 and beyond I'll be happy.