.../... sliding the front section of the drive shaft back about 2 inches. The 46mm nut on the drive shaft forward of the centering ring.../...
A tip re: this joint on the propeller shaft (drive shaft), there is a specified torque from M-B (see BBB) for this sleeve nut at assembly, 35Nm i.e. not very tight. Also, clean the splines and lightly grease them. Why?
Well the drive shaft will adjust itself to a suitable, low tension position lengthwise, for when driving your car. If you tighten this sleeve nut super tight, you will (may) introduce a tension resulting in wear and frame noise.