How many guarts of 75/90 gear oil does a 1999 silverado 4x4 rear end take

if the diff is not leaking oil there should be no reason to be low. If you hear a noise in neutral with the truck not moving, its not in the rear end. it may be the trans or transfer case.

sonds like you may be out of lubricant or even worse pinion gear or ring gear or both could be wore out from running without lubricant. Try filling it to proper level with gear oil usually 50 weight oil but i would check specifications in owners manual. then see if noise continues. good luck.

WELL IF YOU CHANGE THE REAREND THAT DONT HAVE NOTHING TO DO W/PUTTING IT 4 WHEEL DRIVE BECAUSE ITS THE FRONT ONE THAT LOCKS IN . MAYBE YOU BRAKES ARE DRAGGING ON THE REAR END ADJUST BRAKES AN SEE IF THAT HELPS .

Hello my name is Ben. For your truck you will use SAE 75W90 synthetic gear oil in the rear.

Hello, this warning light is for a malfunction in the transfer case control module. this vehicle has a NP8 transfer case system. what you will have to do is to have the transfer case control module scanned for trouble codes. the control module stores trouble codes to help is finding the problem. in most cases on this vehicle, you will either have a code C0327 or a b2725 code stored. code C0327 is for a failed encoder motor or sensor. code B2725 is for a bad control switch

the gears in your rear end are probably chipped and broke or need shims

90 weight oil

The Previous Solution that I sent you was Straight from the Chilton Repair Manual.

Fill it Up to the Bottom of the Filler Cap Opening. Should be 3 or 4 Bottles. Please Rate My Response! Thanks!

There should be a tag on the rear that tells you the weight. It is probably sythetic oil. If there is no tag, call any Chevy dealer, ask for service dept. and they will tell you.