That’s the one thing I really dislike about the C6, you can’t torque it up a hill. Being a three speed it almost scares me when it downshifts!
I didn’t care for the E4OD in the 1994 F250 I had, it was troublesome. It was a 460 with 4.10 gearing also.
The E4OD in my Bronco is great, 3.55 gearing and it will let you torque up a hill to a point. I think the E4OD behind a diesel or 460 is weak and should be “beefed up”.