what would you be confussed about? 1978 had round head lamps . 79 had rectangle. now in late 76 on the f-250 they went from an divorce transfer case to a married one.the kit i am building originally came as a half ton with coil spring.now one thing i am uncertain about was i think all half tons were a married case. as for trim levels custom trim was a small single chrome strip down side of truck between marker lights, ranger trim was a bold chrome strip with a black rubber strip in the chrome. now xlt trim level had all the chrome trim upper ,lower and full tailgate. plus up graded interior trim