Was it an actual Ford bed, or an aftermarket bed made for Toyota's? If may have also been shipped on from over seasnot an could have even been shipped in from over seas. I am not sure, but I think there were some first gen rigs that that you could get a factory stepside bed as an option. I am not sure if it was an oem option, or an U.S. dealer option.

I don't know if anyone actually makes a stepside bed for Toy's anymore, Downey and Northwest Off Road used to list them on their catalogs back in the '90's, but I haven't seen a listing for one in quite awhile.

If the wheel wells and cab line up w/the bed it wouldn't take much to install it, you would likely have to fab up nw mounts, but w/enough efffort and time it could be done.

Check OffRoad.com, a search turned up a discussion about the stepside bed.
This site Action Auto Wreckers in NY builds custom beds that have a military look to them, it might be worth seeing what one costs.