Of those 3 options, I’d definitely do the AX-15 swap, unless you WANT an automatic, then I’d do the 46re. Like MopaR&D said, I’ve been running an AX behind a 5.9 magnum in my Duster for 10 years and 25k+ miles without the first problem. I currently have the car apart for a bigger cam, aluminum heads and efi but the AX will definitely be going back in. I originally had 3.23’s but 1st gear was useless other than starting off on a hill so I switched to 2.76’s. I plan to change my rear tires from 25.5” tall to 27-28” tall in the near future, so if I had it to do over, I’d do 2.94’s.