Couple of months ago I made a thread saying that I wanted to replace my MX518 shell with a G400 shell. (
https://geekhack.org/index.php?topic=86360.0)
Well, just wanted to report that it worked perfectly and I am thrilled! I got it on eBay from a user called angiesonki for $14.90 (feet included). I had been nervous about fitting it, but it was much easier than I thought and I was able to use a standard screwdriver
Now my mouse looks great - nice and neat with none of that irritating "blobby" silver pattern, or orange bits. Just a nice, clean, elegant mouse.
But there was an unexpected bonus… the mouse wheel has been upgraded to a much better wheel! I always liked the MX518 but I had always been disappointed with the wheel, which felt loose and just span around - it didn't really "click" in distinct increments like my previous mouse (the MS Wheel mouse Optical). However, when I changed the shell just now, I noticed there was a metal hook sticking out of the old wheel which wasn't sticking out in the new wheel. (Must have come loose in delivery back in 2009.) Now, this new wheel feels totally solid and has the "notches"!
So I am thrilled about this and would recommend this "upgrade" to anyone. I began this whole process thinking it was time for a new mouse, then I started to read that the MX518 was still popular even today. And now I am more than happy to keep my MX518 - I only wish I had done this a long time ago as the mouse wheel is SO much better now!