Hi. New guy here. I just picked up a 75 Ford F100 last week. This is my first truck and 4x4 vehicle. It has a 351 Cleveland, C4 Trans, and a Dana 20. It also has a detroit locker, 37" tires, and approximately a 9" lift. I have been having problems with the transfer case ever since I got it. At first I couldn't shift it into any gear. To be honest I have no idea what gear it was in when I drove it home but it was working fine. I noticed the shift lever was loose, so I tightened that, and I got it to change through the gears. It was still really difficult to move so I changed the fluid in the TC. The old fluid looked like a gray milky color. No metallic colors though. I put in Valvoline 75w-90 Gear oil and that seemed to help a bit with changing the gears. Anyways my main problem is when I have it either in 4h or 2h the transmission will not shift past 2nd gear. I tried adjusting the vacuum module but it still won't shift. When its in 4h and 4l the front driveshaft is very loud. I tried greasing the zerk fittings but no luck. In 2h it will kick out of gear back into neutral when it won't up shift and it grinds or makes a loud whining noise. In 4l it will shift though all the gears but but the front driveshaft is even louder. I noticed I can twist the front driveshaft by hand back and forth a bit. It seems like the front output might be loose. Anyways that is all I have observed by now and Im at a loss. Any input would be appreciated thanks!