Oil pan differences

[fins2nv]

I am trying to clean up some oil leaks and in the process have done a lot of searching for information. I have a'30 coupe and I haven't been able to find information about my oil pan. I also have the Les Andrews book. Every pan I see is solid, with just a drain plug. My pan has a plate with six small bolts and one large one in the center. I am guessing it has something to do with the oil pump. Anyway, it is leaking oil around this plate. What do I have and is this an easy leak to fix? Any help would be appreciated.