Originally Posted by Scooby
The old AA fittings were longer, you might be able to pick on up from old stock at a local stockist.
If you take your current cylinder to a local machinist they should be able to measure it up & then cut one to fit your cover
There won't be enough material to cut the thread in a 400 style fitting. The pic that Simon has posted above is the right thing. Don't think I'm going to have much luck though as apparently they are no longer available. Still, there must be one gathering dust somewhere.
Yep Simon, as per my edit above, it is one of those. Just need to track one down now.