It was an extra 500 for the soft mopar one but it didn't lock. The dealership offered another hard plastic trifold one that locked but it was 1600 bucks. I'm trying to be around 500 bucks for a locking one.'Most' Rams that come with the boxes I thought were called 'the cargo management system' and comes with a cover? Was yours stolen or did it just come with one?
The bed is an much different with the boxes so you may be stuck with buying a mopar one.
The stock one is a tri-fold and can be locked but like all soft things.....it can still be sliced open.
If you are looking for a good reliable cover that sits flush with the bed of the truck, I highly recommend BakFlip. They make covers for Ram trucks with the RamBox.
I purchased the Bakflip tri fold matte black cover when they first started producing them in May 2016. Awesome product. Easy to install. Looks sharp and clean lines. Latches closed easily. Can open and close the tailgate without worrying about the cover. Needed to add a weatherstrip between the ram box edge and tailgate to completely seal it closed.If you are looking for a good reliable cover that sits flush with the bed of the truck, I highly recommend BakFlip. They make covers for Ram trucks with the RamBox.