If the objective is just to cover the bed in some form, then any small truck shell/topper should fit close enough. Especially since Rangers and Tacomas of that vintage are closer to the same size than they are now.
However, it obviously won't match the body lines perfectly. It might sit a couple inches inboard on the bed rails or overhang the bed rails a few inches, and the rear door might not close or might have a gap at the bottom.
The molds for fiberglass shells have probably been discarded or dismantled, but if you want a new one, a shell with a welded frame and aluminum skin can still be ordered since they aren't made with molds. Tradesman Truck Tops, ARE DCUs, and Leer DCCs are options.