455GTO

iTrader: (18)

Im in the process of collecting all the necessary swap parts for my 4l80e project. I currently have an 02 Trans Am with a T56.

I am wondering if I can reuse my T56 trans mount on the 4l80e...Or if I need an auto specific mount.

Also, in regards to the drive shaft... I've read that the consensus is that you can reuse the stock drive shaft with just a yoke/Ujoint swap... Is the 4l80e the same length as the T56/4l60e to make this a certainty?

Thanks!

FormulaTA327

I think the 80 and 60 are close in length but I belive there are 3 different type shafts on the 80. Stock driveshaft length is what I hear works also. Bmr has the mount, but not 100% sure if it's the same with a T56 to 4l80

kylemm1002

iTrader: (6)

I used a stock 60e mount on my swap. I had an auto car and reused the stock drive shaft with a different yoke.

455GTO

iTrader: (18)

Good info, thanks guys. Anybody know if the T56 trans mount is the same as the 60e?

I currently have 3.90 gears and they are perfect for my t56... Anybody use these or even lower gears with the 4l80e...? Hows highway driving and mpg with it?

FormulaTA327

I think most auto guys use 3.73 or 3.70 if they go 9".

Mystery Bird

iTrader: (7)

I have 3.90 gears with a 4000 TC and once the converter is locked up it cruises nice. I think I get about 18-19 MPG with highway speeds.

455GTO

iTrader: (18)

Awesome info! What kind of RPMS are you turning while cruising around 70-80mph? With my T56 Im right about 2000-2100 at 75...

Mystery Bird

iTrader: (7)

4l80e and 3.90 gears 75-80 with converter locked up should be in the 25-2800 RPM range.

455GTO

iTrader: (18)

Great! That is super helpful.

On a side note... I'm swapping from a T56 and will be installing the factory auto shifter. I am wondering how you guys bolted the factory shifter in place... Did you use self tapping screws? Trying to figure out what screws/bolts ill need to get that thing secure...

Mystery Bird

iTrader: (7)

I used stock stuff so it was already there. Go to a junk yard and cut out that part of the tunnel and weld it in place of your void from the t56.