Well well well.......I posted the exact same question when I joined this site. I have a 1971 Demon that I bought as a project. It too had the biscuit mounts and the through sawybar provision, although it had the old style swaybar installed. No one here had ever seen this so I too concluded that maybe it was a converted spool mount, or maybe an E-body K. The mystery continues...........
340 K frame with swaybar cutouts
