gearing
 

Took the covers off the diffs today. Found 3.91 in front, 3.07 in back. Not good! The front gears look good, the back looks ok. I like the 3.07's in the back with my 4 speed, it cruises at 50 to 55 mph @ 2000 rpms. What I'm asking is what will the 3.91's do out back? Like I said before the 3.91's are in better shape. I know the obvious would be to put 3.91's out back. What do yall think?

Re: gearing
 

By the way the front is D44 5f and rear 12 bolt stock.

Re: gearing
 

Well the 3.91 will get you out of the hole faster, and of course turn more rpms driving down the road. You will have more power, pulling hills and such, also good for towing. Im building my burban with 3.08s in it so I can cruise down the road, not screaming rpms either.

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I called Randys ring & pinion and said could not get 3.91's for the 12 bolt? Didnt think about asking him about 3.07's for front dana 44. For what I use the truck for 3.07's should be fine. Any body got a set?

Re: gearing
 

3.08/3.07's where standard in almost all Blazers, search your local 4x4 clubs B-boards and I'm sure your going to find someone with a axle or 2 for sale. Around here they go pretty cheap on craigslist.

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My first question would be is what size tire are you running?

There is also 22 percent difference in the ratios

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I'm running 265/ 75/16 and might go to 305's. Jeremy

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I've been looking can not find any close to me yet. Salvage yards around here crush things to soon.

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I will/might be looking for a set of axles with 3.08s, I'll see if I can find a 12b with 3.08s, and pull the gears for yah.

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If you go to a 305-75-16, that will be a 34 inch tire. Richt now you have a 31.6 inch tire. I would definatly not go with 3.07 and a 34 inch tire. Big mistake. If you keep the same size tires you will be ok.

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What gears do you think I should use with the 305's? Jeremy

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3.91 would be fine. That way you only have to mess with the one axle.

How does 2500 rpm sound at 65mph.

http://www.intercotire.com/site63.php

Re: gearing
 

Randys ring & pinion said that 3.91s were not available for the 12 bolt rear.

Re: gearing
 

Check for a 3.90 ratio. Probably a hard one to get. 4.11 would be ideal for your application anyway.

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Thanks for the help. I'll let yall know what I come up with. Thanks again, Jeremy