Re: 68 650 shift shaft
When the gearbox is in Fwd, the shift shaft will have a lot of play in it if you try and move it clockwise. If you move it counter-clockwise, you'll eventually feel some resistance. This is the correct position if you were going to install the lower unit with it in Fwd gear.
If you turn the shift shaft a bit more CCW it'll kinda "click" and you'll find the gearbox is in Neutral. It's generally easier to reinstall the lower unit with it shifted to Neutral. Just be sure the control box lever is also in Neutral before you bolt up the lower unit.
To properly orient the shift cam, have the lower unit shifted into Fwd gear as described above. Take a look at the mid-section of the motor and in the front part you'll see a rod sticking out. This isn't the splined shaft that hooks up to the shift shaft in the lower unit, but a solid rod which connects to the reverse lockout hooks.
You'll notice that with the lower unit in place, the reverse lockout rod is heading right towards the shift cam. What you want is, with the lower unit shifted into Fwd, to have shift cam positioned so that the lockout rod will hit the cam about halfway up the ramp.
With the shift shaft positioned correctly in Fwd gear, there is only one way to install the shift cam so it'll work. Any other position will be way way off.
For a more detailed description of how the reverse lock mechanism works, check out this recent thread:
http://forums.iboats.com/showthread.php?t=265380
Note: be sure that when you're aligning the shift cam, you have the shift shaft as far CCW as it'll go in Fwd gear, without actually shifting into Neutral.
HTH & G'luck..............ed
dunno wit way go.