Recently picked up this 1898, which apparently has an original rear sight, minus the sight ladder head.  Before I buy the wrong thing--what is correct?  I have seen a couple images with a three notch head and read other sight heads were also correct.  Serial number is 1905XXX--1899 manufacture best I can tell and 1898 R&C handguard.  Thanks  (I tried posting a photo, but it was too large and my computer skills aren't what they need to be to make the image smaller.)