[Rich 5150 69]

They may have used I`s as a replacement stamp in place of the number 1 due to wear..I have seen it before..these numbers and letters where installed in a jig and hand stamped into the blocks just prior to install into the frame. Also at this time GM was trying to help with vehicle theft with some ( changes ) stamping trans codes into the engine suffix codes II in some cases meant power glide in `65..if we are reading yours right it is the 11 month 04 being the fourth day..