I have an 84 z28 that is all original and going to the boyd shop this winter.I am changing multiple things on the car and the main thing I was wondering about is the front lower valance on the bumper.I was wondering if the font valance from an 85-86 would fit(the longer sleek looking valance) would fit on my original 84 front bumper or would I have to purchase the 85 or 86 bumper to fit the valance.

 

I did the same thing to the 84 I had.I changed the whole ground efx to the IROC type.You will need to get a 85 or newer bumper cover for it to fit right.You will also need the impact absorber bar and the impact cover,the black plastic behind the bumper cover.Oh you will also need the fromt turn signals from the 85 and newer,they sit more flush than the older ones if I remember correctly.If you are going to change the front you might want to change it all,to make it all flow together better.The front as you said is a little more sleek than the older one and dosn't really go with the others pieces that well IMHO.For the rear you have to replace the whole bumper cover because that is one piece,the cover and rear valance are one piece.

Hope this helps man.