So I lifted my 85 cherokee 3 inches last week and I've had problems with my 4wd engaging. It will not go into 4H or 4L. Could it be the slip yoke? T-case linkage?

 

Yes sounds like that to me. Depends on the jeep and year that you need a drop kit or slip yoke. But it seems like your drive shaft is at too much of an angle. But for $ sake I would start with inspecting the linkage. Did it work fine before the lift?

 

Does the shift lever not move or something? Or does the lever move and still no 4x4? The driveshaft length has nothing to do with shifting the t-case. Too steep of an angle would cause crazy vibes. If you put on a tcase drop kit to eliminate vibes, then you probable need one of those brackets to drop the shifting linkage as well. If you didn't but in a tcase drop kit, its probably just a coincidence.

 

Did you put in a t case drop?