An addendum to Valty's great comparison, and also the one he made last year. Here are three flavors of DW cases, all unmodified.
From left to right: DW 6263 (c.2009), DW 6263 (2011), DW 6239 (2011)
Note:
-The older 6263's flanks are about 0.2mm thinner at the middle.
-Smaller indents for the 6239.
-Newer 6263's indents touch the upper edge of the mid-case. In this respect, it's more accurate to the gen than the older case.
-Newer 6263 has more accurate pushers.
-Yes, I know steel bezels should be 6265s, but this case is engraved as a 6263 and DW owes me some acrylic bezels (among many, many other things).