Ok, DD. I'm pretty sure you have an early Model 99 R. Yours was made in 1936 by SN, and the fact that the checkering goes around the underside of the forearm also indicates pre1950(none made 1942-1946). The 99 R's made after 1950 were factory drilled and tapped.
The 99r did not regularly come with a flip up rear site....that was a change made later to accomodate a scope....but yours might have come from the factory that way, I don't know.
You have one of the greatest hunting rifles ever engineered, in my opinion. Everyone aught to have one or two. It is a fantastic deer rifle. Yours is not a collector, so use it. Because it has been drilled through the receiver, it is probably not worth a fortune, but getting $400 would be pretty easy, I think.
Any more questions?
Brian