I messed up when I ordered my 2019.
I thought the same on the gears and mileage so I did the 3.55.
Towing up 6% grades with a 17,000lb 5er, I wish I had the 4.10.
Shifts down into 4th to maintain 60mph.
My 2012 with the 3.73 would hold 60mph in 5th up the same hills.
I see no difference in unloaded mileage between my 2012 with 3.73 and my 2019 with 3.55.
Go the 4.10.
2019 F350 4X4 Dually, FX4, Crew Cab, Ultimate Lariat Package, Agate Black, Black Leather towing a 2006 LE3905 Weekend Warrior
2002 F250 CC, 4X4 - Sold
2004 F350 CC, FX4, loaded - Sold
2006 F350 CC, DRW, FX4 - Sold
2012 F350 CC, DRW, FX4 - Sold