I have seen that steering system and in fact I had a similar one on my 1971 Glastron. If you spin around the ball coupling can you see a set screw?
However, if all else fails you should be able to remove the end cap from the ram. inside the steering cable should go all the way through the ram and be secured by a nut--possibly two. Remove that nut and the cable should slide out of the ram. Then, unbolt the transom mount/swivel and remove the whole smash.
A new helm and cable will cost only a little more than the cable alone. A complete helm and cable will cost around 150. Way back when, it cost me 80 bucks for a cable. If money is not an object and if you want to go a little higher end, you can spend a few bucks more you can get a helm from Teleflex that is all bronze, chrome plated. I salvaged a boat with one of these and installed it into my Glastron. Never looked back and never regretted it.