If your pulling the dash then yes you have to pull the windshield . But if your just trying to pull the heater box out ( maybe to clean it out or change the heater core ) then no you don't have to pull the windshield or the dash . You are however better off pulling the glove box out to get at very thing on the box . Keep track of how everything came off the box so when you put it back together it will make it a little easier . A/C trucks are a little more of a pain in the but . Hope this helps .