You do realise they come in different angles, to match the angle the shroud makes with the deck, don't you. Trafalgar should be able to provide the right ones but it's important to be aware of this if you buy them elsewhere, or if you end up getting them made. In the latter case submit the old one(s) as pattern(s).
Yes that's really why I put in the remark about getting them made.
When we replaced them on the Berwick I crew the owner got them made. It's largely down to convenience. On the one hand you might me able to get them straight off the shelf while on the other you will have to take the old ones, or at least a drawing, in and then go back later to pick them up. OK if there is some where convenient to get them made.
BTW one of ours failed, had we not have noticed we might have lost the mast!
Investigation showed one other on its last legs, it broke while trying to undo the nuts. So we replaced all four. It is our opinion that the failures were associated with leaks. The one that failed was over the galley were the small leak didn't matter and had been ignored. The least corroded was the one above the locker in which I stowed my clothes and which I had therefore removed and resealed some years previosly for obvious reasons.
These types of fitting, be they 'A's or 'U's, should be viewed with suspicion on older boats especially if there is any sign of leakage.
Our all leaked when we bought the boat! Fortunately I have removed them all and checked them and resealed them. My surveyor (who used to work for Westerlys) said that they changed the spec on the later boats and the 'A' bolts were larger and more robust.
Anyway you have made me feel better about our rig, as I have had them all off and obviously gave them a good clean and inspection before putting them back.