The thin metal one is original...
We used to replace them with 1/2" nylon gaskets at the 10 minute oil change that I worked at... We would also sell them a new GM 1/2" drain plug (that came with the white nylon gasket)..
The stock 7/8" chrysler drain plugs are intentionally softer than the pan so they strip out first... They usually get 5 - 8 changes on them before the threads get buggered up...
The GM plugs were harder and wouldn't strip out as easy... Chase the threads in the oil pan with a 1/2" tap (fine I believe) and put the original in if it's in good shape, otherwise go to a
GM dealer and ask for the old v-8 1/2" drain plug...