I’m looking to swap the diff on my obs but I was wondering if I need to swap both diff to the same ratio?also wondering if anyone has swap to a 4:10 ratio

 

Yes, on a four wheel drive vehicle, you must have the same axle ratios front and back, The common GM axle ratios for GM pickups are .308, 3.42, 373, 4.10 and 4.56.

4.10 is really good for pulling heavy trailers, but will decrease gas mileage some when empty, but can actually get better mileage while towing.