In here 340 was actually first one to classify for spring cup welding, not possible in all cars, but for 340 and 360 that is possibility, they don't cost a lot compared to what whole strut is, but it does require indeed welding and one need to take old one out too properly, so that strut is not weakened, of course regulations there might be different, here they examine welds etc visually.
I had close call with this one but I was at MOT station where they did notice how poor shape those were, they did look ok, but did not took too well for ironbar they used, had corroded quite badly, luckily there was less than 1km to mot station from home and garage I used was half way, so I did avoid bursting a tyre.
When you are at it, it is great opportunity to put new front shocks in and also springs as those are not good forever either, with new springs and shocks I found ride to become better, loads better, but then again front shocks had nothing inside of them, but at MOT they were considered better than rear shocks which at the time were new ones
Gas shocks are not very expensive these days and struts need to be taken out anyway so there is not much more work if replaced at same time, that is why worth to put them while front end is apart. Oh and always both sides, also those spring cups, better put new one to other side too even if it would be now tolerable, sorting out those are going to be good for another 10-15 years then, depending of course where one drives and how much.
