Cant tell from these pictures but the replica's I have seen all have a small hole on both sides of the clasp where the "IWC" is stamped. The gen has no holes.
In this link you can easily see the differences. http://forums.watchnet.com/index.php?t=msg&th=273238&rid=0
The replica bracelets are very well done. However, one of the best tells of a replica 3717 is to take a look at the bracelet. You can easily see the holes on the side, no magnifying glass or comparison needed and you can do it while the owner still has the watch on the wrist.
Ask for a sideshot before considering buying!