4wd moving woes

[old Rusty C10]

truck is a 79 k10 longbed th350 trans NP203 t case.
truck was running and driving for days. I park it and put on the plow. it snows 20 plus inches a couple of weeks ago so I hop in try and put it in four low and it wont move all I hear is like grinding of gears . Call up a buddy and he comes over. we jacked up the truck and tried moving the levers on the transfer case and no matter what we did you could push the truck forward and backward even if the trans was in park. Figuring the transfer case was bad I went out and put in a used transfer case. now we can get the truck to act like its in park but if we fool with the levers no matter where we put them it appears that the transfer case is in neutral... sometimes we can get the wheels to turn a fraction of a turn ( while up on jackstands) nothing on the floor When we took out the transfer case it appeared the trans was good no play in the tailshaft. we had 27 splines on the output shaft and the gear in the case.. Any ideas? anyone close wants to look at this thing for me?

[bmchevy1979]

I don't know about the second 203 but the first sounds like my old one the P.O. put gear oil in it instead of 10w30 and with the part time kit it needs to be run in 4wd occasionally to properly lubricate but the gear oil was too thick and it fried the Synchronizers for high and Low and you absolutely had to be rolling to get it to switch between it was a royal pain to have to do and it was anoyying when you were in a bad spot

[cadillac_al]

Does the transfer case lever move? Something should be happening. If you have it running and in drive, you should hear gears grinding when you move the transfer lever. If you do, then put the trans in neutral and move the transfer lever to put it in gear. The shifter in my K15 gets stiff from lack of use because it goes anywhere in high. My K20 gets shifted much more and the transfer shifts like butter. It's pretty hard to spray some lube in there but that's probably what it needs.