Lyman 21 sight markedSa

Gentlemen:
I have a Savage marked (SA) Lyman No. 21 sight which was once on an 1899. Information seems to be scarce. I am hoping one of the forum readers may help.
The sight is in good condition but lacks one or more parts for properly mounting it. The bolt or nut or both that is used to attach the sight to the existing hole in the forward part of the receiver is absent. Normally that hole houses a through bolt that anchors the rotary magazine. What I am looking for is a description , sketch or picture of the missing . There is a picture of such a sight mounted on an1899 on the Savage 1895, 1899 and 99 web site for those wondering what I am going on about. Much obliged for any information.

http://i145.photobucket.com/albums/r...x743282164.jpg