190E 2.3-16 models came with a limited slip differential as the base car configuration (standard equipment) and no other options were offered for electronically controlled ones or plain ones, to my knowledge.
I agree with the MBZ190E16V recommendation, get the differential filled with RedLine Oil Co's limited slip differential fluid, and see if it helps before trashing the unit. I use it, the "shockproof" stuff, and it quieted mine down quite a bit as it had developed a howl at highway speeds that was not so loud it hurt, but it was annoying. Gone now (4,000 miles). See their stuff at www.redlineoil.com.
Good luck, Jim
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)