My truck is the 145" WB with a 5.0L Coyote V8 and a 3:31 diff
The chart sez I can tow 8100 lbs.
That's a load, but not the kind of load you're thinking of.
If I go to a 3:55 RE, it says I can pull 9,500. Say what? All that more for just a little increases in differential?
Okay, now get this -- In an EcoBoost with the same configuration, 3:31 axle, etc, it sez you can pull 9,500 lbs.
Hokay...... The EcoBoost is a strong engine but it isn't that much (if any) stronger than a Coyote V8...... BUT, if you go to a 3:55 differential, it only increases your towing from 9500 to 9800.
Something ain't right. It makes no sense. Everything else is identical as far as I can tell.
Same frame, same 9-3/4 inch rear end... Unless Ford was putting some 8.8 rears on the 2013....?? But I have the 9-3/4 on mine.
And Ford ain't like some of the others -- They don't make 100s of combinations. They usually just make one frame, one transmission, a handful of engines.
It's their 'modular' approach designed to keep costs down.
What I think is that a lot of these towing guides are just that -- Guides. And that they just kinda guessed at some of them