Okay so when I first bought this truck the drive shaft was off but I engaged the 4 wheel drive the light never came on the dash, but I could see that the transfer case was spinning. Later found out the transfer case was bad and when I talked to her owner of the truck before the guy I bought it from he told me the 4 wheel drive worked but the light never came on. I went out got a good transfer case my buddy put it in.I go to pull out of shop engage 4x4 no light no biggie...but no 4x4 either the t case will spin the driveshaft but no 4x4 .
I Have always had air come through the dash vents but now I only have it out of defroster What should I check? I will go posi lok of needed but want to make sure I need to.The damn thing is stuck now sideways half in driveway half on a hill.

You have some vacuum issues. Everything gets is vacuum from the passenger side of the intake. Start there. Chances are, something isn't hooked up, or, something broke, during the t-case swap.