I saw these listed for sale at GSA Auctions. They were originally used on a Kubota RTV 1100 and appear to be in excellent shape. Perhaps they fit other vehicles as well:
https://gsaauctions.gov/gsaauctions/aucalsrh/?sl=51QSCI20328030
https://gsaauctions.gov/gsaauctions/aucalsrh/?sl=51QSCI20328030