stupid question? coil + side?
 

I have a 83SC and a Bosch ignition coil. Today I removed the coil from the fan housing so I could see the marking on the coil to determine the + side from the - side. Well to my dismay it looks like the coil is only marked with the - side is that right? I have a tach adapter coming from Tbitz for my EFI install and the adapter has to be mounted on the + side of the coil can someone confirm this? Or a pic? Thanks