If you had a 1978 ford pickup could change it over to 1973-1977 grille?
No, you can't directly swap a 1973-1977 Ford pickup grille onto a 1978 Ford pickup. The body styles are significantly different. The 1978 model underwent a redesign, and the grille opening and surrounding sheet metal are completely different shapes and sizes. You'd need extensive bodywork and fabrication to even attempt such a swap, and it wouldn't be a simple bolt-on affair.