In a nutshell it's a short wheelbase 92-99 S-class with a 3.5l turbodiesel. Available in 92-93 as the 300SD and 93-95 as the S350. It's a very refined Diesel. You probably couldn't tell it from a short wheelbase S320.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD