PapaSteve

I have a 2000 1500 yard truck that is only used to plow snow. When the front diff stopped 4WD I removed the actuator and replaced it with a welded 'plug' that held the diff engaged 24/7. It ran for 4 or 5 years that way with no troubles. Then the 4WD switches began not working right. I had to push the buttons repeatedly until I could hear it go in. Then it only had 4WD in 4auto a few storms before that quit, leaving the truck functional in 2WD only. I took it to a repair shop, my guy said the transfer case was bad. So I had him put in a used one. I told him to remove the shift acutuator from the TC and lock it into 4HI manually. That done, still no 4HI. The front drive shaft makes a clunk inside the TC when wiggled like it is engaged. What am I missing?