According to my Merc. manual, it says to just disconnect the end fitting at the engine side (which I've done), remove the spiral wrap inside the boat, and pull the cable out from the transom. It doesn't mention any other operation.

But, as in the pics, the cable at the engine has a barrel and a nut. The barrel looks to be permaswaged on at two points, so not sure about unthreading it.

At the transom end, obviously it's too large to fit through the bellow.

Anybody know how to do this?

The threaded barrel should unthread from the brass cable end.

If you don't have the correct plyers for the metal clamp (shift cable boot) you can use just a zip tie, I know marinas that just do this. Thats what on mine and been holding fine for years. Last boat I did I used a pair of plyers the best I could for the clamp and used a small zip tie next to it.

a clever guy can put the shift cable bellows on without taking the cable out .takes a little time but it will go over the end of the cable on the bellhousing side .done it many times when in a hurry and the boats gotta go

How's that? I would think there's a risk of tearing it on the hex, as it's much larger than the bellow i.d.

What's bizarre, is that Merc could have used a much smaller hex there, to enable this easily.

loosen the jam nut, the threaded section where the
barrel is will then screw out.

Replace the whole aft shift cable as they typically get damaged when pulling it out. Be sure to make a snake from the old inner cable to pull the new one back through. -Otherwise, you are in for a headache getting the new cable back in and routed correctly.

+1

Unthread that barrel then pull the inner cable out, leaving the outer housing in place. Now thread the inner cable back into the housing from the engine side. When you pull the outer housing hold the inner in place and then thread the new outer onto the old inner and up to the engine. Then pull the old inner and push the new inner up from the transom side.

Just curious, why would it get damaged? Thx!

Many times you have to tug on it pretty hard to get it out. -If it's factory, there's a spiral protective wrap around the outer jacket down low that gets bunched up when pulling it out. They don't last forever. When it's time for the shift bellows, everything else back there is on the way out too.