lethalbit, 
So, it seems like IDC68 for internal SCSI connections was a common thing?
But as far as I can tell only the IDC50 header was ever actually standardized for internal unshielded connections (believe me, I check)
I wonder if they took the existing external HD68 or VHDCI68 pinouts and just used those, i've not checked that bit, but I suspect they did.