Yup my 69 and 70 T500 frames have them too. It could have been anything really, from a company stamp to some pre-assembled parts inspection etc. No one will know this for sure as its one of those obscure things.
Yeap My 69 and 70 frames have them Also.My guess is to tell which side of the Plate is the Outward facing side.I sat and Pondered on those stars back a few years ago when I stripped my 69 Frame.I figure if it were an Inspection stamp they wouldn't have been as Careful as to Place the star in the same Exact Position every time.I'm sure all of the Holes in the plates were stamped from a Single Die.I'm Thinking that the Star was Part of the Die to Mark the Part for Placement. Just MY Opinion.I could be completely wrong.
Hang me from the Tree of Shame.Damn! I forgot the Rope.
I've been cleaning them up and re-welding some of them, the welding is so bad all the ends have creater cracks, no down slop on those MIG welder in the 70's and all the weld spatters unbelievable.