Ok well, the 05 sierra.... Ya drivetrain was not built to handle the heavy body. Currently i am working on my daily driver, and the transmission is far below par. I have the 4L60E and am looking for something that would give the truck driveability and offer the ability to handle power, or the ocassional romp on the pedal without hesitation or odd shift points.. I looked into a shop that claims their rebuild will handle up to 750hp (which is double my truck). However i questioned them and they state that the tranny shifts smoothly and will handle most vehicle up to 750hp but still drives like a caddy when just rolling around. It seems the vast majority of people know little to nothing when it comes to the topic of automatic transmissions. I have not yet been through my auto trans course and so am not going to build mine just yet, i going to put something in and build mine on the side (as the learning curve increases i will become more proficient). This will also allow my truck to remain on the road and not have to find other means of transportation, as it is my everyday user. Anybody that can shed light on either a good source for dependable auto transmissions or if you have any insight on the G-Men transmissions... I am all ears!