M-4384 is the Answer to my question. Thanks to all that helped me find the information!!

I recently purchased a small collection of porcelain insulators with some multipart pieces included. The insulator is missing the 4th skirt, makes the ID very difficult. The insulator looks like the M-4420 Thomas pieces, but not sure what the 4th shell was like if it was extended or hidden like the M-4420's. This is the first of four pictures of this example and hope there is some help with the M Number as well as some rarity info. Here is also some of the incuse that is ledgible and they are very old, ???? 24, 18??, ???? ?? 1896? ???? ??, 1897, JUNE 7, 1898 ???? 9, 1900, APRIL 30, 1901 ???? ??, 1902, F. M. LOCKE

The next set of photos will have the picture of this embossing. Thanks for looking and any help with the ID of the insulator.