Changed my transmission fluid/filter yesterday, and noticed some engine oil on the cusp of leaking where the engine/trans meet. I'm thinking this is the lower pan gasket? 74k miles, 2017 L5P :
UNBOXING a 2020 Duramax L5P Oil Cooler - YouTube
2020 Duramax L5P Oil Cooler Upgrade | NC4x4
2020 Duramax L5P Oil Cooler Upgrade | NC4x4
A Close-Up Look At The L5P Duramax V8: Video | GM Authority