Is there any way to change them out without removing the dash or windshield? I bought replacements and just looking for the simplest way to do this. Thanks!

no actual 68 dart experience but does it look like if you undid the tinnerman nuts underneath that hold them on that they could come up from the dash enough to clear the windshield? Likely there would be a picture on ebay of em that to scale would get you a good estimate as to how tall they are. EDIT missed that you already have new ones in hand.

They will come out like said above but are a real biotch without removing other things like the radio and/or glove box liner...

Thanks guys. I'll start with the passenger side and removing the glove box liner to see how that goes. It should give me a good indication of what will need to come out on driver side, like you said, radio, etc....
Wish me luck!