Thank you all for your replies and help! It is really appreciated! I have found out a few more things about this revolver that I was not aware of. It does have the folllowing:

1. Dovetailed adjustable TRITIUM night sight.
2. Factory Comp.
3. Radiused underbarrrel lug.
4. Radiused charge holes.
5. Radiused combat trigger.
6. Radiused hammer.
7. Trigger over-travel stop.
8. Full LEngth Ejection.
9. Uncle Mike's Grips
10. Full length ejection.
11. Performance center logo.
12. Round butt stainless "K" frame.
13. Cylynder latch cut for speed loaders.
14. 3 digit special serial number in the low 100's.
15. The unusual feature of this is the rear sight is the newer version with the rounded front edge, and subsequently the top strap is drilled and tapped for a scope mount. This feature did not show up until the 66-4 engineering change in normal production.