I did the search but cannot find info on this. When I removed the fill-plug, I noticed a remnant of an O-Ring I think. I went to Ford and they do not have part for the 7.3 but had something for smaller engines. No luck with NAPA either and I did email Bob the Oil Guy but no reply yet. All he has on his website was a gasoline and oil resistant thread sealer.

Thanks in advance.

 

I'd try the one listed for the gas truck, tranny drain plug is probably the same.

 

go to the local hardware store, not home depot. they should have boxes of various sized o rings. try that.