I have a 96 Chevy Tahoe 2xwheel drive 5.7 vortex 4l60e trans and I need a new rear end can I get better mpg?

If you always drive your truck unloaded on the open flat highway a higher speed set of ring and pinion gears "might" benefit you. You didn't list what ratio was in the rear-end now. If you're not sure, take your VIN code to your Chevrolet parts counter.

I'll be perfectly honest with you: Your truck has an overdriven four speed transmission. If it has 3.73 gears or higher speed (3.42) I would leave the rear end alone. Look at your tachometer when you're going 55 mph. I'll bet it is barely cracking 2,200 RPM. If your truck were mine I wouldn't touch it if your were lukey enough to have 4.11 gears in it. There are plenty of other low cost ways to raise fuel economy. AC-Delco ignition wires and spark plugs, 5W-30 full synthetic oil, synthetic rear-end lube and transmission lube. Remove the tail-gate or drive with it down. raise tire pressures within 5 puonds of maximum printed on tires. Change the fuel filter and air cleaner. Run some 3M Total Fuel System Cleaner through the fuel tank with no more tham 14 gallons of fuel. Little things add-up.

Ring and pinion installation should be left to an experienced mechanic. The large ring gear may be required to be spaced closer to the pinion to get the proper wear pattern on the face of the gear teeth. The pinion gear sometimes must be spaced in or out to get the proper heal and toe pattern when setting up the gears. A dial indicator and machinists bluing on the gear teath must be used to define the driver and coast pattern as well as the heal and toe pattern.

I suggest you read all you can on Ring and Pinion Installation before jumping off the deep end.

switching to a higher geared rear end will make your car travel at the same speed as before with a lower rpm. You will not be able to change the gears yourself. The bearings are pressed in and you would need some advanced mechanical skills. im guessing right now you have 373 gears. if you went down to like 342 gears you would save maybe 2-3 mpg. I doubt its worth spending $ 800 dollars for that when you can get the same increase in mpg with a k&n cold air intake, which only costs like 250-300.