No teardown pictures of the Classic 3G have been found yet. There is, however, a basic guide of the non-electronic differences by iLounge. Since the model number is the same as the Classic 2G, there probably aren't any worthwhile (if any) in the hardware.
By iPod classic 3g we mean the re-introduced 160GB version of the classic which was announced on September 9 2009. It is the same size as the Classic 2G.