Because the bulkhead panel behind the seats on an 88 is further forward when compared to 109, the short cab overlaps the bulkhead panel behind the seats on an 88.
To fill this gap, Land Rover supplied a flatish panel that fills in the gap left between the bulkhead panel behind the seats and the back of the shortcab that is unique to the 88.
I don't think the 90 uses the same panel on ROW as thinking the bulkhead panel behind the seats falls in the same position as the 110, but could be wrong regarding the 90.
Uncle "Richard" Douglas has a Land Rover with big wheels that never gets stuck... until he breaks something so it won't go. Uncle Douglas always breaks something. - Anna Crowther at the Conclave 2012 (AKA Carburetor Neck)