Strange that they'll mix aluminum tubes and steel lugs. that's just asking for corrosion between the two dissimal metals. Strange too that they would be providing bolts to de-mount the trear triangle. I would think that the (single) bolted joint would have been a major weak point in the frame. Maybe that's why the frame could be a rare one. The details don't make too much sense.....so far.
Pics please!!

Chombi
84 Peugeot PSV