As far as I know, the Ranger only came with two bed lengths. Long, and normal. As a matter of fact, I've never even seen a Ranger (in picture or otherwise) with anything else but the standard size bed.
Normally it's a problem of finding a bed topper/cover that will fit the stepside bed, which is substantially narrower than it's flatsided counterpart. For bedrails though this makes no difference as the overall length is the same.