Sorry for the very late late reply... They should only have been riveted. The repair shop send me the procedure and it only state rivets, no welding at all.
Olivier

I have just bought a 1996 E300D and have read all of the horror stories about spring perch failure.

I have just had to replace both front springs, due to one of them being broken, so have had at least a visual inspection of them.
It appears that maybe they have had some extra welding done on them in the past, as there is signs of some MIG weld beads inside the bottom edge of the spring cup itself, and the lower mounting points to the body also look MIG'd rather than spot-welds.

Alot of my driving is done on mid-high speed 'A' roads, with lots of bumps and dips in the road, which makes me concerned about the perches ripping off.

I was looking through WIS and saw a reinforcing panel, used on 'Special Protection Version with light armoring' (Document ar62.10-p-0006-01e).

I do have skills in welding and bodywork, so was wondering if it would be a good idea to install these pieces, if they are still available, just for peace of mind.

Well I ordered the reinforcement plates anyway... they came to a very reasonable £5.33 each ($9 USD), and the rivets were £0.01 each (less than 2 cents), lol.

I think i'll feel alot happier about driving the car over rough ground once i've installed them. I studied the WIS yesterday, and I think my spring perches have definately already been replaced due to the MIG welds, where the original welds would have been spot.

Will take some pictures of the installation process and post them.