I have a metal ribbed bed in our 54/3100 the PO installed it. It fits fine (after rebolting it to the crossmenbers) but I have always wondered from what year truck did it come from???? The ribs run the length of the bed and it seems it could have been a two piece affair with the shorter piece towards the cab? I like a metal bed no maintenance issues and it can be removed for a wood plank model if needed.... T/C Steve