Originally Posted by
bluenote157
The only other thing that stands out is a raised heart shape on the down tube facing the road. It is place roughly where some down tube shifters would typically mount. Any one got any clues?
That is a stop for the clamp-on shifter band and would make me say a 70's Japanese frame. You'll need to post photos for any more details. Close-ups of the seat stay tops, drop-outs, and lugs.