my wife and I installed a set of firestone air bags on the rear of our 2005 colorado, crew cab, before installing the air bag suspension, my truck would bottom out, when i had a trailer hitched,we have a pop-up camper we use to camp and go to races the tongue weight only @ 100 lbs, total trailer weight is 8000, my rear gears are 3:73 according to chevy, my colorado does a great job pulling the weight, 8000 lbs. seems like a lot but when you add all the camping gear ect. it adds up we also have a propane generator that comes in handy, the firestone air bags do a great job suspending the rear of my truck, and the ride is 100 % better i highly reccomend the bags on every truck that pulls a trailor or hauls a heavy load., i have been told by a transmission shop my automatic tranny will be ok as long as i downshift when pulling hills and when decending down hill, i do not have a tranny cooler any advice from you tranny experts would be welcome