How to install shift shaft into 1973 Mercury 1500 Outboard

[baxleyrc]

I've dropped the lower unit on my 1973 Mercury 1500 Outboard. How do I align the lower unit gear system before installing the shift shaft? The shift shaft is located on the upper unit and fits into a hole into the lower unit. How do I align the lower unit gear train with the upper unit shift shaft? It is a blind assembly.