Ive been looking around the board for a little while but most info seemed to be for a car, but my question is what would be the best ratio for my truck in terms of power and mpg, it is a stock /6 and has 2.94s right now with 4spd manual trans. Its a good truck but has no power going up hills and not much power pulling a trailer. And is it possible I could nab a set of gears out of dakotas? I think a few of them used the 8 1/4 rear, thanks!

well a set of 3.xx would help the grunt but its will be a trade off for mileage... cant have both normally with out an overdrive trans.. i wouldn't use anything lower than a 3:50 gear set if mileage is that important to you... My 2c....

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MRO....

Cheap, Fast, Reliable.... Pick 2...

Which 4-speed? The Granny low NP435 or the A833OD? If you have an overdrive I would use 3.90s or 4.10s. There are a lot of Dakotas with 3.90 geared 8 1/4 axles. 3.55 was common too. If you have the NP435 with a 1:1 high gear I'd use 3.55s since you plan on towing. 3.21s are also out there, but that's only a 10% increase in torque multiplication over the 2.94s.

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Joshua

If you have the 833 od with a stock tire size I would go with 4.11's,anything abouve a 30 in tire I would go 4.56's.

I was happy with the 4.10 in my 81 with OD trans....I do have them for sale check parts for sale '81 truck parts'

Yeah I have the 833 with OD your thinking a 3.91 or 4.10 would be best with that then?

Final ratios in OD would be (assuming stock tire sizes):

3.91=2.85 (so similar to a vehicle with a automatic or 3 spd with 2.94 gears-maybe a little more mileage for cruise on the flats in OD, a little
less help if the truck is loaded and getting it moving from a stop).

4.10/4.11=2.99/3.00 a couple more rpm than the 3.91 at cruise, but if you have a load in the truck it will be easier to get the truck rolling.

4.56's @ OD is similar to auto with 3.31's...if you increase the tire diameter this goes back toward the other ratios above


-D.Idiot

I think Id be leaning more towards 3.91 then, as of now I'm getting a little over 15 mpg, would this drop much with 3.91?

My '73 with a 318, came from the factory with 3.55s as part of the towing package. Even with a slant six, I don't think I'd go lower than that. It tows fine, but is a bit too thirsty when running empty.

It really depends on several factors. One big thing is that the power valve stay closed during cruise. If the power valve is open frequently now you may get better highway fuel economy with 3.90 gears than 2.94.

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Joshua

Alright well thanks for all the input I'll try and get some 3.91s I think they may help alot, whenever I drive in OD it's almost always pinned to the floor to keep a constant speed

4x4 dakota`s had 3.90`s and 2wd had 3.55`s with 15" wheels

Are there any dakotas without the 6 bolt wheel pattern so that I could just swap the entire axel? I that would probably be quicker than changing gears.

91 was the year the dakota went to 6lugs so before that they were 5lug with 4.5" bolt pattern. not sure of track width but i know the 96 is 9" wider than an A body 8 1/4, the 97 on new style are wider again.

I think ill just take the time to remove the gears then, thanks again for all your help guys!