From left to right:
Broken Campy seat bolt,
Replacement Campy seat bolt,
Alternative M8-1.0 mm threaded allen head screw (35 mm, Grade 12.9, Zinc finish. Fastenal item # 0142067).
P1010987.jpg

The Fastenal bolt fits when tested in the 1988 Campagnolo Chorus aero seat post. It is slightly longer than necessary, so protrudes a bit further above the top of the seat rail clamp. I reinstalled the Campy NOS bolt, and am carrying the Fastenal as a backup in the tool pouch on my bike.