[Healeys] Drive shaft bolts

[john spaur]

I have two different bolt sets for the drive shaft. One set is 
standard hex head. The other set is 1" long with a "T" style head 
meaning that it is flat on one side and it meant to set against the 
flat of the drive shaft u-joint to keep it from turning when 
tightened (it will not accept any type of wrench).

Which end of the drive shaft is this bolt for; the OD end or the 
differential end?

Thank you,
John Spaur
'62 MK II