8 1/4 ring and pinion from 2000 durango

[74swingerlover]

i have come across a 8.25" Posi Differential from a 2000 Durango. I was wondering if it would fit/work in a '74 8.25?

And if it does fit, what is the stock ratio I should expect? Looking for something a little get up and go over the 2.76 non posi

 

[cudamark]

The ring and pinion will swap if you include the carrier. As for get up and go, it will depend on the difference between the two ratios. If you're pulling out a 2.76 and installing a 3.55, yes, you'll get a lot more acceleration.....but worse mileage and more engine wear. That's the trade-off you make. If you're pulling 2.76's and installing 2.94's, you probably won't notice a whole lot. If you're pulling 2.76's and installing 2.45's, it will more of a dog off the line, but your mileage may improve. Remember, you'll need to get a new speedo gear too so you'll know how fast you're really going!

 

[daliant]

The ring and pinion will swap right in. The carrier on a '97 and up 8 1/4 takes 29 spline axles so unless you plan on buying new axles it's not going to work, your 74 8 1/4 has 27 spline axles in it.

 

[cudamark]

You can't swap out the side gears for the correct ones?

 

[daliant]

I guess you could if you can find a pair.

 

[superdart]

If that unit is from a Durango, I would almost guarantee it is at least a 3.55, and MAYBE a 3.91.

The posi unit would require custom axles to achieve the 29 spline pattern you need. My car is currently undergoing this mod, and I ordered my axles from Dr. Diff. If you run the diff, you will need to know the diameter of the center pin. There were different versions. Mine in particular was a narrow pin version (with the pin being almost .10 inches narrower than my stock '75 pin), which allows for a thicker, stronger "button" on the end of the axle.

Stock axle versus new axle: