Air conditioning parts help please !

[72 K20]

Hi everybody !!

Working on the 72 and found that the diverter door that is located on the right side of the truck inside the cowl has a dried out gasket /seal. I haven't had any luck finding this ,,, can you buy a new seal or do you have to purchase the complete assembly ? What is the proper name for it ?

And while on the subject of seals/gaskets does anyone offer the seals/gaskets for the other blend doors like the defroster ?

Also ,,,, is this something I should invest in ? http://www.classicparts.com/1967-72-.../#.VTwh7Gd0zzA I'm planning on running a serpentine setup and a later model compressor like a 95 chevy truck would have.

Thanks in advance for any and all help or pointers !!!
Have a great day !! Tom