I would like to change only the heating and AC part of my dash to a fourth gens...Is this possible and has anyone done it? If you have please post pictures.

 

It would take alot of work/fab to try and make a 4thgen hvac control work. The electric/vacuum is pretty straightforward.
The closedt thing I found was the controls from a corsica or lumina (forgot.. been awhile). Still had to modify it with 4thgen controls and, the trim plate still has to be opened up slightly.
Here's the only crappy shot I have of it..