The Mercedes 280SE, SEL, 4.5 liter V-8 engine sedans (W108 chassis) have the 3.27 ratio. They were only produced in 1971 and 1972. Earlier euro versions had a 3.5 liter V-8 with a 3.47 rear ratio. These will work well also but are scarce.
Things to watch out for.........
Make sure it is coming out of a W108 sedan with a V-8 engine (the six cylinder version do not have the right ratios)
Make sure no to get an air suspension rear differerntial by mistake (W109 chassis) it will not work.
Watch the rear diff. video so you will know how to check the rear diff for excessive "lash" play caused by a worn casting in the diff.
Always check the ratio stamped on the unit before you buy!