Will an 85 -90 z-28 air dam fit onto a 83 z-28 front fascia?

 

Nope! You'll have to get a whole different nose.....a 1985-1992 nose will work.....

 

If you are talking about the lower air damn commonly used for cooling, they are all the same and the air damn bolts onto the bottom of the radiator support. That is the only technical part of the car considered an air dam, hope this helps