Suggest you do a lot of research on this one before you commit...
Below you will find the ratio differences between a 6L80 and 4L80
Along with some other thoughts....
6L80/90 boxes are a totally different animal build wise from a 4L80 style...
6L80/90
Note...Notice no 1:1 in this trans
4.03
2.36 -- 58.56% (high) RPM Retention 41.44% RPM DROP
1.53 -- 64.83% (high) RPM Retention 35.17% RPM DROP
1.15 -- 75.16% (high) RPM Retention 24.84% RPM DROP
0.852 -- 74.09% (high) RPM Retention 25.91% RPM DROP
0.67/.70
4l80/85
2.48
1.48 -- 59.68% (high) RPM Retention 40.32% RPM DROP
1.00 -- 67.57% (high) RPM Retention 32.43% RPM DROP
0.75
Hope that you know that 6L's will not work with LS1 based engine.
If your going to put LS2 in front of it check with Mast Motorsports or others and make sure their ECM will work with it.
Mast Motorsports are the only one I know of that claims to have LS 2 ECM that will work with it.
Only GM's LS3/7 or 9 ECM work with it.
