They are different. I have a set of wheel openings off a fleetside laying in my garage. The fleet is about 36" at the bottom, the Burb/panel is under 33" - the molded piece at the bottom is also a different profile, especially behind the wheel. There is enough of a difference that somone who knows burbs/panels will notice. If your not worried about then they will work. I would love to have that fleetside bed so I vote for not cutting it up.....with all that said, I saved the wheel openings off the fleetside bed just in case I end up with a burb that needs quarters.....the rest of the fleetside bed.....well its in transformation phase for my 57 LCF.