What is the size of the oil plug on a 4.2 engine? Specifically mine is 5/8 but I would assume there was a standard size over the years? The oil plug "resides" in a 1968 4.2L
I think it has been drilled out to this size and retapped by PO. The female thread is seriously worn and I would insert a helicoil thread repair but it appears they are not available at such a large size.
Given the above, any suggestions for my dilemma?

Paul Rodman
68 OTS

 

The stock drain plug is 5/8x18 UNF.

 

Thanks John.
Never gave it any thought before, but that is a large plug. Not sure how I can rethread this.