I am trying to decide wether to go with a T56 or let Cahill Performance Transmissions do his magic to my T56. One reason I want the 6-speed (besides the fun of shifting) is I need the 6th gear overdrive because I put a lot of highway miles on the car going to school. I also would like the quickness of the automatic though. I was wondering if it is possible to change the overdrive ratio of the 4L60E. Help me decide if you will, Thanks Chris.

 

I run t56's in two of my cars and I love the shifting and the deep overdrive, so I would say stick with the t56.