I've seen them listed in Sales Brochures as early as 1976, but as a dealer installed accessory. I never saw them very often until they started using them on a lot of Vans, Suburbans, and Blazers around 1987.
It is my understanding there are two versions that look basically the same from the front. An earlier version made by Alco with a forged rim, and a later version made by Western that was cast not forged. Mine are the Alcoas that I found on facebook marketplace that had been sitting in the woods or at least a decade. Then i cleaned them up, sanded out any curbing and polished them.