Thanks Mike and Harold. Yes, the inner sleeve is thinner metal than the strut tube. Any idea how and where this inner sleeve is held in place? There's a definite gap between it and the strut tube but it seems to be rock solid.
I'm just making absolutely sure this tube is actually removable before I have a crack. i.e. not welded at the bottom or something! Once I attack this tube, there's no going back!!!
If I do successfully remove the inner tube, It will mean quite a gap between the new bilstein shock and the strut wall. Is this right? Should there be a 2-3mm or so gap around the shock and the wall?