Small letter G style from 1957, unposted, marked DIF (Dearborn foundry).   Tabs measure 1” plus so I don’t believe these have been milled.    One chamber has some pitting due to moisture.   Otherwise, the heads look good to the naked eye, FWIW.   I wish I had a magnaflux yoke to thoroughly inspect.  I don’t think it makes sense to ship these due to the weight.   Local pickup encouraged.    Or stop by on the way if you are going to the Thunderbird convention in Texas in September.  PM if any questions or for more pictures.   Thanks for looking!