That's a good question. I don't think anybody is reproducing them these days. The Flareside step bumpers were dealer installed aftermarket items, they were never sold by Ford.
I'd try looking for them for the smaller trucks, like Rangers or Chevy S-10's.
1994 F150 4x2 Flareside. 5.0 w/MAF, 4R70W, stock.
1984 F150 4X2 Flareside. Mild 302 w/ 5spd. Sold.
1980 F150 4X4 Flareside. 300i6 w/ 5spd. Sold in 2021.
1980 F100 4X2 Flareside. 351w/2bbl w/NP435. Sold in 1995