Which carrier do you have? The part number on the carrier is cast into the drivers side right behind and below the pinion snout. The last 3 numbers are what the carrier is usually referenced by. Any ratio of gear can be installed into it's respective carrier... for instance, if you have a "741" housing, any gearset that fits a 741 housing can be installed. You will need both the ring gear and the pinion gear of the same ratio to do the swap. Your above question makes no sense, you cannot rebuild a 2:76 gear to be anything other than a 2:76. You can however find the same numbered housing and use a 2:76 gearset in it, and use another housing to put a different set of ratios into, like the above poster mentioned. Then you simply remove and replace the carriers with whichever gearset is appropriate for your intended application. Good luck with your project, Geof