S41 - the D's never went to Desert Storm. The E/F versions had a detuned version of the avionics on the D. There is a great history at this link:
https://acc.dau.mil/CommunityBrowser.aspx?id=37599
There was a plan to fit the FBs, Ds, Es, and Fs with a common modernized avionics suite in the 1980s, but I believe that the post-Cold War drawdown cut it off before many actual mods had been carried out.