Received a response from Sampson in less than 30 minutes today. Would be awesome if they had an old set laying around.
"We are aware of the issue, and it is why all the Sampson cranks were sold with precise mounting instructions ---and all cranks sold after 1995 also had a full warranty registration that required the installer to sign the form and fill in the torque setting-- While it is standard now for cranks to have a torque setting-in the 1990's most people ignored it, and the result would be a fracture as you describe, which was the result of simply pushing the cranks too hard onto the taper of the bb-
Can you provide me any information as to when you purchased the cranks, and who installed these and on what type of bb? And DO NOT RIDE these cranks, they are subject to fail at anytime per your description. "