4.11's are the killer almost anything is better than that. I swapped from 3.25 to 2.75's in my 77 with a 351M and it was alot better. I think by looking at your engine there you have a 351C or a 351M either way the MPG is in the rear gears right now. I would even leave the trans alone for now. Go with anything but the 4.11's good GOD mate !!!
