Rear-End Gear Ratios

[marek4792]

So it appears I just had a differential failure it started hollering for a few hundred miles when I would put the pedal down in the middle of nowhere (I-84 Oregon) got into Portland got a green light and as soon I loaded the clutch " bam bam bam" got another driver to get the trailer. I could move but not really fast with a very light foot and had to lock the power divider to go up inclines.

My question tho I'm running 3.42 Rockwell gears which puts me at 1500 at about 70mph with 295 75R 22.5 drive tires the next ratio available would be 3.21 (no 3.36 available from Rockwell) which unless I want go 80 at 1550rpm everywhere seems extreme for a truck that goes 48 states unless putting it in direct (8LO) on a 13 speed. Would I be better off sticking with the 3.42 or switching them out for the 3.21 and run in direct in the 65mph and below states and possibly sacrificing pulling power at the same time? I pull van/reefer at varying weights up to 80k gross.