If you want to build a Season 1 replica, the Marc Brown Front Bumper with Grillbars and Turn Signal Blackouts should be your first choice.
For a Season 2 replica, KITT has different looks, so you can choose the Marc Brown front bumper or the Knight Passions “New Model” front bumper - both with grillbars.
For a Season 3 replica you can choose the Marc Brown front bumper or the Knight Passions “New Model” front bumper without grillbars.
If you like the look of KITT in Season 4 then the Knight Passions “Season 4” front bumper is your choice. This bumper is not available with grillbars because KITT never had grillbars in Season 4.
The Knight Passions “Classic” Front Bumper is a little “sharper” than in the TV show, but it also has its own beautiful look. If you prefer this, you can build Season 1-3 with this type of front bumper.
Either way, the important thing is that you build your replica the way you like it and the way you want it to be.