The distal end of the shift shaft is splined(slides out of the lower unit) and the proximal end remains attached to the power head when the lower unit comes off. Some has said that the shaft should not be removed from the lower unit when removing it. This is not possible in a 1979 20 hp (likely the '78 as well). So, I am wondering is these people are incorrect, or will the cam shifter gear really come out of place and the lower unit then need to be taken apart and the cam realigned.
From the repair manual diagram, it looks like the shifter shaft has a set screw connecting it the head linkage and that it can be removed and used to shift the lower unit into neutral for reassembly. I haven't had the chance to look yet.
racerone, any thoughts? I can't imagine that that cam would pop out of place so easy, but then again, I wasn't the one who did the disassembly. The guy that I purchased it from said the gears all worked and that he was just unable to get it back together b/c the lower unit would not slide on all the way.