I have a 2004 dodge CTD with 3.73 rear end when i tow my 5ver in tow haul mode my rpm,s are runnibf 2500 rpm at 60 62 mph, sound about right? truck is a 4speed auto
my chevy 6.0 gasser w/ 4:10's pulling @8000lb TT runs about 2500rpm at 65mph on slightly hilly north east hits 3000rpms at 7% grade 45mph with or with out tow haul. for me it just streches out the shift point on my 4spd tranny. I use synthetic oil and tranny fluid if that matters.