Seven Sparta Tie Down Anchor for... https://www.amazon.com/dp/B07H9ZKRH6?ref=ppx_pop_mob_ap_share

here you go. i scuffed mine with some sandpaper...sprayed high heat primer and then sprayed enamel. i tend to overdo things. you will have to take the washers off the bed bolts which is not an easy task. also you will have to use a step-bit to widen the holes. Im sure you can find other D Rings that fit without modification, bit for me, elbow grease is free.