I will ramble a little here. The differential carrier bearings install in the axle housing. They have shims behind them on both sides. The bevel gear to pinion gear should have about .006" to .009" backlash. That is accomplished by proper shim size on both sides. The proper thickness axle housing gasket also plays a roll. The thicker the gasket the more you will affect backlash.
Was there not a piece of the old gasket you could check for thickness?