Originally Posted by Jerry in SC

Spec. Ord. (should be on the printed label) is often mistaken for Special Order. The number under Spec. Ord. is the date the revolver was boxed at the factory, it's present on most, if not all, modern S&W labels.

The big difference in the 63-3 and earlier models is the improved yoke retention, it has a V in the yoke where a spring loaded ball in the yoke screw rides. Since the screw is larger it's nigh impossible to get them mixed up (pretty common) and ruin the fit of the yoke. You will see 63-3's with hard chromed or case colored hammers and triggers, with wood stocks or Uncle Mike's rubber stocks.