Old propane tanks on new RVs

I would bet at some point the OP swapped out his original tanks at some big box store, and was handed older replacements.

I highly doubt the dealer (In this case Camping World, who are the exclusive distributor for Coleman branded TT's made by Dutchmen Mfg.)sent a crew down to Ferrellgas or somewhere to search out the old tanks with the intent of saving two cents per bottle.