MafiaTiger, i don't feel this is a stupid question (few months ago i asked the same question here on simv forums ;)).
The altitude callout is part of GPWS (Ground Proximity Warning System).
-----> All you have to do is download the GPWS for your aircraft (Boeing, Airbus, Mc donnell or any other) from SimV, avsim etc.
-----> Then add the sounds (which you downloaded) in the sounds folder of FS2004.
-----> You will now need to edit the panel.cfg - editing here means adding just one line at the bottom of "[Window00]" i.e., gaugexx=FPDA_boeing_callout, 169,649,10,9, (here xx is the subsequent guage number)
-----> That's it, you have the GPWS in the plane.
Hence by editing the panel.cfg, you can have the GPWS in any aircraft you want.
Hope i could solved your problem ???
If not, just read the read-me file provided with the download

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