Based on what I read in the Year One catalog (yes, relying a parts house catalog):

"Front Spoiler for 1969 Trans Am Models. Although only correct for the 1969 Trans Am, the spoiler will fit 1967-1968 models with the small panel below the front valance panel (most A/C and 400 cars came with this extra pan)"

Not sure if above is correct, new to this and been kicking around the idea of front and rear spoilers (I won't get the discussion going again on the rear one, my decision is getting past drilling holes in my perfect deck lid and going against the PHS)