Before, I had a dipstick problem. It wouldnt register the oil i poured in. Got a new dipstick and its the same length so that squashed that idea. Only thing I can think of now is it has a different oil pan.
I was told if a magnet sticks to it its the original one and my parts guy at my job says it might be an ecoline oil pan?

It has a 4.2 engine swapped in, might be a newer version of the same body truck. Still unknown