Differences between 1896 and 1900 Spencer Shotguns

[Roscoe Coles]

Does anyone have a pencer 1900 pump shotgun?  I need some information about the block in a 1900 and the differences between the 1900 and the 1896.  As far as I can see the 1900 has two extractors (one on each pump rail) and the 1896 has one (only on the right rail).  The bolt looks a bit different between the 1900 and the 1896 but I need to know if they are interchangeable.

Roscoe