Originally Posted by Steve-W
The recall for low rear axle lube was on the F53 chassis. Not an issue with the E450 the OP has.
Ford's recall affects many models beyond the F-53 and includes the E-450. 2021 was the last chassis year on the recall, but checking the gear oil would be a good idea. The OP's chassis model year may be older than 2023. The following are copied and pasted.
Ford has recalled nearly 180 model year 2020-2021 Edge, 2020 Lincoln Nautilus and Ford Escape, and 2021 Lincoln Corsair and Ford Bronco Sport vehicles. Ford says the rear drive axles may lock because an inadequate amount of lubricant is in the rear drive units.
Ford Motor Company (Ford) is recalling certain 2020 F-550 and 2021 E-350 and E-450 vehicles. The rear axle differential fluid may be below the minimum level, possibly resulting in a failure of the rear axle assembly and driveshaft separation.