The replacement hose from Walck's is a rubbery accordion affair, and the diameter has to be stretched a little to fit over the collars at the front and back of the engine compartment. This is hard to do in the front because there isn't room to work. The easiest way to manage the installation is to remove the collar from the back of the grille. It is held in place by three phillips screws put in from the front. Once the hose is attached to the collar, the collar can be reattached to the grille. It's then an easy matter to attach the other end of the hose to the collar on the firewall.Like Nugilo said, original for cold air intake to heater. Should have had a screen over it and flex hose coming from it originally.