Something to check before following Irish Ramblers advise on removing the coupling from the shaft.
I have a Bene, and removed the coupling two years ago to replace the
shaft seal (I have a Vetus seal on mine).
The coupling is secured to the shaft by a bolt which threads into the end of the shaft. You cannot see the bolt, but after disconnecting the coupling from the
gear box side, slide the shaft aft a couple of inches, and you can feel the bolt
head inside the coupling.
Bit of bother this as you have to somehow lock the shaft to stop it rotating while removing the bolt.
Did mine with the
boat on the hard, and used a length of baulk of timber wedged under the prop to keep the shaft from turning.
If you are in the water, put a couple of bolts back in the coupling flange, place a spanner over one bolt with the shank of the spanner jammed under the second bolt to prevent the shaft turning. This is a lot easier with two pairs of hands.