What viscosty is the rearend fluid on 3500 chev?

The recommended viscosity for the rear end fluid in a 3500 Chevrolet truck typically is 75W-90 or 75W-140, depending on the specific differential type and operating conditions. It's important to consult the owner's manual or a service guide for your specific model year to ensure the correct fluid is used. Always use a high-quality gear oil that meets or exceeds GM specifications for optimal performance.