1) The RFP 742 is freeware since about 2009.
2) (Airplane) Models can't be easily extracted from .mdl files. There's tools to view them, but the export function always leaves you with an unsmoothed, untextured and cluttered model without animations.
3) Maybe the OP wants to use data extracted from the 742 for modelling systems for the FG 742?
There's a tool named Blckbox which can display and log the values of variables used in (a) specific gauge(s), but it only works for XML based ones.
Since the RFP 742 most probably uses the closed .gau format, BB isn't of use.
For FS2000, there's Gaugedump, but I'm not sure if it works for FS8/9 version gauges.
http://www.bruceh.com/gdmpdoc.htmlMaybe the web has more...