The originals are basically iron swing bolts (gate eye bolts) but they were rotten. I couldn't get hot dipped ones long enough, long ones were all ZP coated and stainless ones were something like 90 sterling a piece
and having them made would be quite expensive.
I decided to cut an off-cut off the 1 1/8" propshaft into segments and bought 316 stainless bolts to weld to them but then decided that 1 1/8" looked too small. I then went and bought a meter of 50mm x 10mm stainless bar and spent the day making up these.
This is the full assembly. The skewer came with the boat. You line up the eyes then drop in the skewer to keep the rudder in place.
The rectangular half will be bolted through the transom and sternpost and the round side through the rudder.
They're fairly robust, The round eye on the pintle is a 25mm long piece of 40mm 316 driveshaft, The bolts are M12 316 about 7 inches long and the skewer is 13mm diameter.
This is the upper pintle, The transom sits at a slightly different angle to the lower half of the stern post so the top one has to stand out an inch further to keep the pivot point in line with the skeg. Now I can finally scratch them off the list.