Automatic transaxle, 3-speed (THM 125C, later named 3T40)

1996: standard on the sedan only; shared A-body transaxle code, cited from the Chevrolet Celebrity kits: 1984 from its own option line (the air-conditioning entries of 1985–1989 list MD9 only among several engines and units, which dates no year, and the Celebrity pages of 1985–1989 sell the unit as MX1); 1982–1983 and 1985–1996 from the parts catalog and Wikipedia's Turbo-Hydramatic 125 article, which gives the THM 125 to the A-body 1982–1996

GM engineering code on the Cavalier power-team pages, the unit the order guides sell as MX1; matched to the Skyhawk's unit by meaning: Wikipedia's Skyhawk article names the 3 speed Turbo-Hydramatic 125C in its infobox but prints no code; each page prints its own model year (1986, 1987, 1989); the kit's power-team line for the 2.0 L engine reads "Avail (MD9)" in 1986 and 1987 and "Optional Hydramatic (MD9)" for the LL8 in 1989; 1984–1985 and 1988 are left out because no listed kit page heads the code on a single-condition line for those years; shared J-body code; cited from the Chevrolet Cavalier kit

GM engineering code behind the MX1 merchandising option; matched to the Skylark's unit by meaning: Wikipedia's Skylark article names the 3 speed Turbo-Hydramatic 125 automatic in its infobox but prints no code; the Citation kit's automatic-transmission weight line for the 2.5 L engine reads "Merchandising Option for MD9, MX1"; 1983 is left out because no listed kit page heads the code that year; shared X-body code; cited from the Chevrolet Citation kit