In response to an inquiry of David O DODD's monument I had the following reply this afternoon from Director of MacArthur Museum:
I have attached a photo of the Dodd marker. As the inscription indicates, it was erected in 1926. Despite the marker's current location on what is now the parking lot of the UALR Law School (once St. John's College), the actually site of Dodd's hanging is beneath what is now the I-30 access road just east of MacArthur Park.
I don't know where that might be, but living in southwest Florida I won't be driving around to find it.