Truck Wont Move !!!!!!

1989 Chevy K2500 4x4,just Put In Transmission And When I Went Down The Road For A Test Drive It Seemed Like Someone Put The
Truck In Park While I Was Driving.if Its In 2-wheel Drive And The
Tranny Is In Drive It Wont Movelike If Something Is Holding It.
When Its In 2 Wheel Or 4 Wheel Hi Or Low And Tranny Is In Neutral If You Try To Push It You Cant,like If Its In Park Or Something.
If I Put The Transfer Case In Neutral Then You Can Push It.it Does Make A Winding Noise When I Accelerate.when I Shift The Tranny In Gear You Could Feel It Shift In All Gears So I Dont Think Its The Tranny.i Did Forget To Add Some Fluid In Transfer Case.is It The Transfer Case Or Could It Be Something Else?

1989 Chevy K2500 4x4,just Put In Transmission And When I Went Down The Road For A Test Drive It Seemed Like Someone Put The
Truck In Park While I Was Driving.if Its In 2-wheel Drive And The
Tranny Is In Drive It Wont Movelike If Something Is Holding It.
When Its In 2 Wheel Or 4 Wheel Hi Or Low And Tranny Is In Neutral If You Try To Push It You Cant,like If Its In Park Or Something.
If I Put The Transfer Case In Neutral Then You Can Push It.it Does Make A Winding Noise When I Accelerate.when I Shift The Tranny In Gear You Could Feel It Shift In All Gears So I Dont Think Its The Tranny.i Did Forget To Add Some Fluid In Transfer Case.is It The Transfer Case Or Could It Be Something Else? my buddy had the same problem and thinks its the t case cause when you look at it its twisted up on the drivers side and the pass side of the case is twisted down

Could be a broken snap ring http://www.drivetrain.com/gillies/Tcasesaver.html

//2000CAYukon