I have an automatic 98 2500 club cab 4x4. 5.9 diesel that is having isssues. I replaced all the vacuum lines that go from the firewall that connects the cruise control and a/c down to the actual harness itself for the tcase and then the front axle lines that run by the frame to the front axle. Here’s what is still wrong. the line that connects to the evaporator from the a/c vacuum harness is bad because of rodents. The tcase shifter won’t go into 4h and i looked and it doesn’t seem to be anything caught by the linkage. Maybe underneath the boot? it doesn’t feel like the 4wd engages at all when shifted into 4L. I looked at the vacuum switch atop the tcase and it was pretty dirty and I cleaned it out but the ball feels pretty tough when I pushed down on it. I haven’t checked the cad and that my be my next thing to look at. I’m still relatively new to mechanics so explainations are helpful too. Any suggestions would be great!!