My s10 was making a roaring noise an when I was going to work one morning it made a awful clunking or grinding noise I pulled over an cut it off when I cut it back on put it into gear pushed the gas wouldn't go anywhere but when I finally put it in 4wd drives fine but still makes a noise when I push tye gas when I stop pushing the gas it stops also noticed before this happened there was grease under towards the rear end an I don't wanna replace the whole rear end or front if I don't have to any suggestions please

 

Sounds like you need to pull the rear differential cover and assess the damage inside. It sounds like there likely is damage to the ring and/or pinion gear.