chiropractor

Yup, that is the knocking sound! I was going to take mine back to the dealer tomorrow believing that it was a rod bearing spun!!! Only have 200 miles on my LTZ 3500. It is sad to say but I'm happy that your truck is making this noise too. Truly, a rod knock has a more metallic clunk to it, this sounds much like an air compressor piston pumping if you were to eliminate the electric motor and belt sounds!! It almost has to be some sort of pumping sound for oil, antifreeze, transmission cooling or something like that. Yes, the 2020 engine is the same as 19 however the changes include enhanced cooling and the new Allison 10 speed. Maybe GM could explain!