Yes I know I have one and it was in the truck. Last oil change I asked my neighbor who is a mechanic at a Kia dealership to change the oil. I gave the plug to him to use. Truck came back spotless. I left the plug in the truck.The OP has a Cummins and that looks about right below where the oil filter is.
There are plugs for changing the Cummins oil filter that allows you to remove the filter without making a mess. Chances are the previous oil change tech didn't use or have a plug for the filter.
2 years ago I was in CT visiting family and had the oil changed at my son's shop. I told them about the plug and they bought one. no mess.
The service writer's only comment was "we change oil in these every day. I don't know what the problem is".
Sorry, rant over.