Looks like it is massively out of hydro (was due in May of 1998, unless there are other Hydro markings not in the picture). Are they Aluminum (hard to tell from picture) or steel. If they are steel, there would be much less problem,... if Aluminum, it may be very difficult to get filled. There is a lot of controversy about Pre- 1990 Aluminum cylinders (Luxfer & Walter Kidde). There were some that were made of a bad alloy & have the potential to rupture. A lot of shops will not fill them because of this, that is if they can even pass hydro. If they are steel,.... well, I’ve seen some older than this come in & pass hydro.