The 4t65e with the 2.93 final gear ratio goes with the 3.1 Monte LS. The 3.8 has a 3.29 final gear. In order to do this gear swap and have it work without throwing a cel code you have to have the computer ECM program changed. Also, in doing this swap you are decreasing the performance of your Monte SS. I'm surprised your Trans guy didn't explain this to you. Even the 4t65e HD has a 3.27 final gear.

 

First I have the 3.4L. Second, I have no idea what the gear ratio is for the 4T65E that came with the 2000 LSs with the 3.4. Milzy has a choice of 2.86, 2.93, 3.05, or 3.29.

 

https://montecarloforum.com/forum/en...on-info-34514/

The above post explains the final gears for each version of the 6th gen Monte.
Sorry for my mistake. I had just woke up when I read your post. I had not had my coffee yet! Lol.
I believe the 4t65e - HD has a shorter cv axle on the right side. And the ECM has to be reprogrammed for that trans otherwise you get a CEL code.

 

So, I could could get away with a gear change without reprogramming the ECM on my 2000 LS?

 

If you change the final gear, you have to re program the PCM.

 

OK. Stick with the stock 2.86 so no reprogramming is needed.

 

Update: Ordered a 4T65E transmission from Milzy Motorsports on Thursday. It should be here either Wednesday or Thursday. I ordered it with the stock 2.86 gears.

 

Update: The Monte was flat-bedded to the shop about 20 minutes ago. The transmission will be put in and should be ready to go by Saturday. It sucks when there's only one full timer and two part-timers that work at that small shop.

I am planning on taking my car on a nice long ride after this.

 

I know you can't wait to take your Monte out for that nice long ride!!

 

It looks like after almost two months of the car being down and the car sitting at the shop for 3 weeks, that the Green Mamba will be coming home on Wednesday.