So it looks like someone has replaced my primary filter with a secondary??
If that came out of the filter assembly just below the Generator then yes its the wrong filter type. The small filter sits high in the assembly so that water can collect in the bottom and not be sucked into the fuel line leading to the other fuel filters. That is why its important to drain your primary filter frequently especially if your truck sits outside or you use alternate fuels or fuels from questionable locations. You might just want to consider doing the spin on filter upgrade for the primary filter rather than try to get the parts to make your assembly correct for use with the correct primary filter.
I will be doing the filter upgrade on my next change. There are a couple of members that sell the kits here's a link to one:
JATONKA MULTIFUEL SPIN-ON OIL FILTER KITS
You can also check the SS classifieds.
Good luck !