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Discussion Starter #1
Im looking for somone that has swapped for 2 1/2ton rockwells. How much did it affect your fuel milage?
Do they come with a rear locker? and what gear ratio do they have?
 

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They do have 6.72 gears.

I never thought I would see "fuel mileage" and "Rockwells" used in the same post... what next, who makes the best aggressive highway tires to use on Rockwells? :lol:

Most people with Rockwells run about a 44 inch tire, and then the gear ratio is what it should be for a tire of that size. If you are running 40's, 42,'s 44's, or anything bigger... fuel mileage shouldn't even be in your vocabulary at that point. You either want good gas mileage or you want a big truck on Rocks. You can't have both, and usually you can't even have a stock truck with good mileage. I don't see why you are even worried about that.
 

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On 2005-11-27 13:23, latest project wrote:
i believe that they came in either 6.72 or 6.17, one is just much more common than the other

All 2 1/2 ton rocks are 6:72 gears. ALso like danny said unforunately you cant have both so just go for the rocks. :bigthumb:
 

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Discussion Starter #10
well I doubt Ill ever put them on my truck. not sure how much they cost. ide be only running 39.5's maybe move up to a 41" irok.
 

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On 2005-11-27 11:52, djgaston wrote:
They do have 6.72 gears.

I never thought I would see "fuel mileage" and "Rockwells" used in the same post...

When MPG stands for minutes per gallon, you know you're running Rockwells.
 

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On 2005-11-28 17:14, HaWiiLuVeR wrote:
dont you need 44" tire to keep that pig from dragging on the cement? :flipoff:

better clearance than a 14bolt actually
 

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On 2005-12-01 21:51, NickM wrote:


Your kidding , right? :bluecry:

nope, with the top loaders and planetaries, its about an inch more clearance
 

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And with custom diff covers, you gain another 1 1/2 inches. :D:
[img=500x167]http://www.usa6x6.com/images/PAN%20measurement.jpg[/img]
 

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Drag it over enough rocks and it will grind itself down. :D:
 

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On 2005-11-28 17:14, HaWiiLuVeR wrote:
dont you need 44" tire to keep that pig from dragging on the cement? :flipoff:

I think you're talking about d80's. :silly:
 

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Rockwell 2.5 tons have 6.72 gearing. GMC 2.5 tons have 6.17 gearing. The Rockwells are the top loaders and the GMCs have a front load 3rd member (like a Ford 9"). There is much more available for the Rockwells as far as aftermarket parts. I don't think any of them came with lockers, but a Detroit can be added. It fits in place of the spider gears and reuses the case just like a 14BFF does. A very good source for aftermarket parts is Ouverson Engineering. They make billet shafts in stock or 2" sizes, lockers, spools, hubs, (all with alloy material), and a sweet 8 lug conversion hub that allows use of an 8 x 6.5 lug pattern.

We put a Super Duty with a PSD on Rockwells and 49s. If I recall it gets about 12 MPG. Not bad for a truck that size. I think properly matched with correct tire sizes, the mileage can be decent, but overall it's just the axle and size you'd want and not worry about mileage.
 
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