Originally Posted by Lowestoft Mike
Ok, Mark, and Capn Morgan
, thanks for that. I understand what you mean, but my coupling is made of metal, with bushes mounted in rubber, inserted in the metal disk, as per the attached picture. So, thin metal disk with bushes running through, mounted in rubber, and as you correctly say 2 flanges, each with two bolts - yokes, effectively. If there were 4 bolts per flange, life would be a lot easier.
Since starting this post, I've received the replacement part, and as your post suggests, it's made of some sort of flexible material, hmm....
It would really be nice to have some pictures of your couplings, since you haven't IDed your motor/tranny. But this is likely pre 1975. These flex couplers were used on old Austin cars.
If you have two flat surfaces on your metal couplers, normally the procedure is to pull the shaft forward until they meet and line them up that way first. There should be enough distance between your prop and cutless bearing to do this (1-1/2 X shaft diameter).
Conventional couplers have a register on them, one male and one female, to keep them on center to each other. Once that is done, then the use of the feeler gauge is used to square up the faces. Then you have to check center again and start over.