i have a 90 stepper with this stock bumper...
just today on my way home from work i passed a beautiful jet black '78 stepper with a small lift that i have never seen before( i know ALL the nice squares in my town!), & i noticed he had a later bumper like mine mounted on there, & it looked great! tucked in nice on the ends & looked totally factory.
i'm sure he probably had to modify or fab the mounts.