In the '70s (and before) I remember all brands of pickup trucks often wearing rear bumpers that were installed at the dealership. Usually these were painted instead of chrome and would have the dealership name stamped into the metal. My Dad's '77 GMC had this. Dealers were happy to install a chrome rear bumper...for a small fee.
The nicer, more upscale trucks arrived at the dealership with factory chrome bumpers. And of course the Blazers, Jimmys and Suburbans had the rounded bumpers with no place to install a trailer ball and required the installation of a Draw-Tite type hitch.
I know that it is popular to install the Suburban/Blazer style rear bumper on a square these days but that is not how those trucks looked back in the day and not what I wanted for mine.
The Westin brand that
@mtbadbob recommended is probably your best option today. And happens to be what is on my '87.
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