Thanks folks for the help. I did end up getting a set of used springs thru car-parts.com with 44k on them, they arrived on Friday. I think the reason so many of these are failing is they stamped, I would guess a part number. in the last coil and I feel that is setting up a stress area.

Thanks too for the offer of the slk front and rears, if I didn't already have the others in my hands i would have bought those for sure. I thought of just grinding off the last coil end, but was concerned that the ride height/camber will have changed, and my camber had been borderline on the last alignment. My hope is the old springs were weakened and these "newer" ones will put me back into spec. Hope to install them later in the week.
You guys are always a great help!