I would look at the T56 Magnum as this: A 4-speed with twin OD's. So, honestly the big advantage to it in my case was 2-fold, I run 3.23 rear axle gears so the 2.97:1 first makes it hit a little harder at the beginning and easier to drive, and it has a .8 and .64 OD. The .8 OD is great for 40-55 mph and the .64 is good for 65+ MPH. Here in MI I drive a lot of 45-50mph roads and the freeways are 70 speed limit, 70 mph is 1900 rpm for me which is ideal. My engine is totally fine with 1500 rpm running so it helps a lot there.