Hello Alan,
no I don't think they have. I'm not sure if it was with the advent of the 4.2 litre engine, where the bore spacing were altered slightly, they may have had a sealing issue with the block distorting.
I'm not sure about stainless fasteners personally, they have their own problems, especially where heat is involved. Stainless can be brittle and threads pick up quite easily.
Alec