You must be from the U.K because you called a Mercedes a Merc. In the U.S., Merc (pronounced "merck") is our slang for a Mercury, a division of Ford.
We usually call a Mercedes a "benz", or shorthand on the site is MB.
The last year of the W124 in the U.S. was 1995, and the last revision debuted in 1994 models.
There is a nice thread where every member posted pictures of their cars. If you scroll down, you'll see it. There must be 10+ pages of owner's cars, and there are several pictures to look at.
It might be expensive to buy everything, but I believe you'll need the lower body cladding and license plate insert that showed up in 1991. Then starting on 1994 models, they got new completely painted bumpers, a new hood with recessed grill, European style headlights (yours probably already has these), new almost clear corners (lane change indicators) with a sliver of amber (93 and older corners were all amber in the U.S.), new trunk lid with chrome strip under star symbol instead on the long black plastic strip, new tail lights that are red and clear (93 and older tail lights are red, clear and amber).
Interior changes included more wood on the dash and doors (arrived in 1991??), and in 1993 the final interior changes included passenger side airbag, new armrest with flip up lid revealing a storage compartment, and a storage box on the center console under the armrest that has a locking sliding wooden door. I believe this was added because the passenger side airbag took the place of the glove box. This storage box was available on models prior to 93 as an option, but came standard from 93-95.
Last, a new engine was installed in 1993, the M104 3.2 liter engine in place of the 3.0 liter M103. This M104 engine continued in the W210 from 96-97, and a 2.8 liter version of the M104 was used in the 94-97 C280.
Just another encouraging word on trying the search function. This site has so much participation, that it seems everything has been discussed in great detail a lot. If you like discussions on oil, oil quality, synthetic vs. conventional oil, oil change intervals, changing oil when hot, etc., do a search. You'll spend more time reading these posts than sleeping. And you'll thank God for Larry Bible.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".