mercedes84black

I started to hear a grinding noise from underneath and the car was straining to move when given gas. I put it up on 4 jack stands, put it in drive, gave it a little gas and all 4 wheels barely wanted to turn and with the grinding. I'm assuming since it's all 4 wheels doing the same thing it has to be the tranny or transfer case. The 4 wheels seem to turn smoother when allowed to turn without giving it gas. Any help would be greatly appreciated in advance