Question about non OD 833 and rpm range

yes i have done several of those and comes back as me having 3.9 diff gears or rpm should be around 2700, so im a little confused
You probably have 3.91's and not 3.55's like you said. You can jack it up and turn the wheel while watching the driveshaft to confirm the ratio. Both wheels will turn the same direction with a Sure Grip.