Can I use an auxiliary transmission with an auto tranny? I am gear bound when I come out of overdrive on hills in my 57 LCF. I am running a 350 with a 4l80 tranny and 5.38 gears 9r22.5 tires. I am comming up over hills pulling my camper at around 50 mph and the 350 is tacking pretty high. As soon as I get back on the flats it shifts into overdrive and I can cruise right along. I do not want to swap out the rear because I think I will not be able to get going from a stop. Camper is around 9k pounds.