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· Registered
131 Posts
Discussion Starter · #1 ·
i have an 04 dakota with the 4.7 and the 545rfe w/ 3.55 open rear end. i live in the heart of the applachian mountains therefore i don't do a lot of long flat highway running.

My issue is that i don't have enough power once i get into fifth gear with lock up. it drags ass going uphills until it drops substantially until it gets to the shift point, then it shifts to 3rd and pulls hard until it gets up to correct speed.

i have read about people going and updating their 45rfe to the 545rfe because they get the second overdrive. I want to remove my second overdrive and go back to the final transmission ratio of .75 like a 45rfe.

i was contemplating a rear end gear updgrade but with a 4x4 you are talking $$$. i thought if i could just get it flashed with the old programming, possibly i can get my rpms into the right range w/o doing a major gearing overhaul.

sorry for the long post, anyone have any insight?

· SRT-8 Dakota
815 Posts
cant do it unfortunantly because the type of computer you have in your truck. It is known as the NGC controler which is both engine and trans computers in one unit unlike the older trucks that have two seperate computers. As for your situation i would recomend a gear change. I had the same issue on flat roads with a load on the truck and with a slight incline. It just loaded the truck to much. I went with 4.56's and absolutly love them. I only noticed a slight decrease in gas mileage about 1-1.5mpg which was worth it in my opinion. You could go with 4.10's which would work ou well if you dont do alot of towing/racing

· .:.:.:.:.:.:.:.
8,002 Posts
Yeah, you can't do it...

Gear change is your only option and, if you do it for gas savings, it'll take forever to get a ROI.

3.55 is a ridiculous gear ratio for these trucks, especially on a 4x4 with 31"+ tires and a double overdrive. With my 265/70-17 tires, 4.56 gears and 5th gear programming, I turn 2K at 60mph. It's great, never shifts down.
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