It should be a straight forward swap. The 114.010/011/015 chassis all had 3.92 ratio. The biggest jump in ratio in standard US models would be to get a 3.46 differential out of 115.114 chassis 300D. All 123 differentials also would work and the 85 300D had a 2.88. The 82-84 300D had a 3.07. They all will fit in the car. All of the imput flanges are the same.
Bosch Master, ASE Master, L1
33 years MB technician