Hey my name is XXXXX XXXXX im here to help. here is the information you seek.
Front differential- GM 7.6" ring gear 10 bolt cover
carrier breaks-3.08 and 3.23
spline count 1.438/27
no pinion support
Rear differential- GM 8 inch ring gear 10 bolt cover 28 spline axles c clips
carrier breaks -3.08 and 3.31
spline count 1.438/25
Not sure what you are refering to by slower gears
But remember in aXXXXXvehicle your front and rear gear ratios need to be the same or extremely close so that damage does not occur to the transfer case.
what needs to be done is look on the marking tabs on both of your differential covers and there will be numbers that closely resembly the carrier brake numbers but they will not have a decimal.
you will be able to find exaclty what you need there. good luck with your vehicle!