"T-Cup" oil drain sump, weld-in metal cup.
This is the part of the pan that the oil drain plug threads into. (Drain plug part number 3080E.)
If your sump has bad threads or is damaged you can replace it with this... OR...
This can be added to later oil pans to make them look like 1909-1913 pans. This is a good heavy machined sump, not a thin stamping. Has an excellent edge for the plug gasket seal.