The six speed is the best for towing hands down.Any auto is a compromise,but towing abt 7 to 9 k I have no serious complaints with the 48re . I haul up fancy gap and black mtn. and monteagle a good bit and I assure you i never let off the pedal. I'm not sure why you would, unless the curves were only possible at 50. I hit the bottom of fancy gap at 70mph ,its 8 miles to the top ,about 3 miles into the hill the tranny shifts from 4th to 3rd and holds it to the top ,running abt 60 mph.I haven't climbed any hills that I needed to let up on the pedal to the point the tranny would shift into od,but there's a lot of hills I haven't climbed,most hills are pulled in 4th with a shift down into 3rd and back into 4th at the top.,but I'm only pulling moderate loads,might be a whole different ball-game with max gvw. If I ever need to tow 15k on a daily basis .it will be with a medium duty truck and a stick shift.

 

I am in the process of buying a 10k 5er. I travel the same hills you do. I'll see how my 4.10s like Fancy Gap.

 

my 05 48re drove me nuts with the back and forth shifting from 3rd to 4th when we where going up to alpine arizona with the switchbacks and sharp curves and up and downs pulling 12000lbs trying to maintain 40-45mph. it got so bad i just slowed down to 35mph and ran it in 2nd until i got on some strait road

 

I travel those hills too. The 99 w/4.10's yanking a 7k lb TT would pull it at 60 mph in OD mashed to the floor all the way up. Occassionally, it would jump from OD about a 1/2 mile from the top. Tranny never got hot. It pulled Black Mtn at 55 mph, OD off, and again, mashed to the floor. The 03 has never pulled either mtn and I have a heavier TT (8200 lbs), so I will expect the same or better come early spring.

 

Black mtn. is a nasty hill. My 03 6spd.,required shifing into 5th to maintain 55 up that hill,with about 8k load.

 

Again guys , it depends on your load and the road. The 2005 has lots of power and will pull a good load up a good hill in 4th . but when you hit that ballance where it starts to hunt gears you gotta be able to lockout 4th and make it stay in 3rd.

 

bump

 

Since pecandude1 went and bumped all the threads concerning the 48RE,,,,, I figured I would give my Dad's feedback after he and Mom got back from their trip to CA and back home to VA.
Dad has not stopped talking about how well the new truck performed. I never thought I would ever hear my 76 year old father use the phrase,,,, "That new transmission and diesel engine is just AWSOME!" I had told him of all the info that I had read about concerning the differences in this trans and the 47RE he had in the V-10. He said he quickly learned the right "touch" on the throttle for the various situations and he was very impressed with the performance. No gear hunting and good hold back on the down grades.