The 7.5" version has a ratio of 3.91, there is also a 7" version of which the ratio is 3.92. The 7.5" version you will probably only find on the Scorpio/Granada mk3. The 2.9 versions had a 3.64, so I expect that the 3.91 is on the 2.0 and maybe also 2.4. And if I remember correctly there was even a Scorpio 1.8, which will probably also have the 3.91. Because I don't think there is a shorter ratio used on these cars. The later bug eye Scorpio does have shorter ratios at 4.07 and 4.27 I believe, also both for 7.5" diffs.