I know essentially nothing about the Collins 51 stuff, but I believe some of it is similar to the R-388 through R-390 stuff. If this is the case, those manuals have just been added to the Trackpads site as PW protected .pdfs. PWs available free upon request: (see instructions on site) http://www.trackpads.net/webs/wireless-set-no19/index.htm -John