Your car most likely had the 4T65E-HD (code MN7) is a heavy duty version of the 4T65-E,
transmission. Other GM midsize front driven cars that used that were the v-8's and
super/turbo charged v-6's. Most the others of that time frame used the 4T65E, (4 - forward
gears, T - transverse, ## - GVWR, E - electrically controlled) These tranys had 4 different
converters depending on engines and other options, and could have as many as 12
different final drive ratios., I would research the specific model you have, (options sticker
on your door jam, or somewhere hopefully) look for v-8's, and SS's (malibu, and impala
were 2 very produced vehicles so I wish you much luck. I have a 2006 3.9 LT impala, love
it.