2000 Monte Carlo transmission issues
 

I recently purchased a 2000 M.C. LS 3.4 liter. I've been having issues with the transmission. I takes a while for it to shift gears, usually between 2500- 3000 rpms though all gears. When it does shifts it's somewhat hard, but not real bad. I've also noticed it has quite a whine to it until it warms up. I live in Wisconsin so it's around 20-30 degrees right now. I've dropped the pan and changed the filter and fluid, I didn't do a complete flush though. I didn't see anything out of the ordinary in the pan. What needs to be done to fix it?

Basically, its old. I dont know about what mileage you have, but since you are not OO of the vehicle, it might be time to overhaul the transmission or the like.

Is your speedometer reading?

Yes, the speedo is reading

I should also add that it had a used trans installed in 2015 that had only 112000 miles on it

I've been told that the trans has the wrong gear ratio for my specific model, according to the code on the trans and the options listed for the car. The shop I took it to found a diagnostic code P0730.Has anybody heard of this?

This is what I read "The Engine Control Module (ECM), Powertrain Control Module (PCM) or Transmission Control Module (TCM) uses input from various sensors to verify the correct operation of the transmission and its components. Engine speed is often calculated against the transmission speed sensor to determine gear ratio and torque converter slip. If the calculation does not match the desired value, the Diagnostic Trouble Code is set and the Check Engine Lamp is illuminated. Incorrect ratio codes typically require an advanced mechanical ability and diagnostic tools."