'69 F-250 Axle Question

[ToughOldFord]

Posted this at a different forum with no results, hope you all here can help me out:

Okay, I've been playing with the idea of putting some higher gears in my 1969 F-250. It currently has 4.10s in it and I was thinking about going to 3.55s. Don't have a tach in it yet, but you can hear the engine screaming at 65MPH.
In the past when I've done rear end work I've just replaced parts from axles that have had the same parts so now I need to know what my availability and interchange is.
Are the ring and pinions in an F-250 exclusive for that axle or can I use ones out of an F-100, F-350, etc? And what is the span of years I can use on my truck? Any idea on what RPM change I'll see going from 4.10 to 3.55? Is there a better recommendation than the 3.55s? And this is a Dana 60 9.75 correct?
TIA!

[1970F250]

you could just get bigger tires

[ToughOldFord]

[67F250CS]

Hang in there a few minutes more. Someone with expertise will chime in Im sure.

[heep70]

to the site. Please feel free to hit the "Welcome Mat" and tell us about yourself and what Ford you own. This will help us with your question.

A D60 is a D60, you can only use Dana 60 R&P. No other R&P will enterchange. If you change carriers watch out for spline count on the side gears. You have a 16 spline D60. Some axle shafts are not enterchangable because of lenght differences. I can't remember which years, makes and models. Something to watch out for.

Use the calculator in the link below to figure out your RPM.

http://www.csgnetwork.com/multirpmcalc.html

Some good info here. http://www.ring-pinion.com/default.asp

[fordloaf]

[quote="1970F250"]you could just get bigger tires[/quote]


I have a 4:10 and bigger tires and i can run at 75 mph just fine.

[ToughOldFord]

Okay, thanks for the info.
Now, just being a 9.75 doesn't make it a Dana, correct?

[FORDification]

A Ford 9" has a smooth round surface on the back and a removeable pumpkin on the front, whereas a Dana has a rear-mounted access cover.

[ToughOldFord]

Couple more questions:

Is the nut holding the yoke on to the pinion shaft a normal or reverse thread?
I'm not getting the one on the donor axle to budge. My next step is to heat the nut and put a cheater on it, but I want to make sure I'm going the right way.

And is there anything I should look for that would limit interchangeability? My truck is a '69 F250 and the donor truck looks to be a 71 F250, but I notice that the yoke nut on the donor is larger than the nut on mine. Could there be other differences that will make the swap not possible? Or are all the parts in these Dana 60s interchangeable? (Not including spline count of course, I'm only after the ring and pinion)
Thanks again!

[heep70]

you might run into bearing size differences and brake componet differences. The centers and axle shafts are all interchangable.

[ToughOldFord]

Right, but the only thing I'm using off the donor axle is the ring and pinion. I just wanted to be sure that the new ring will bolt up to my carrier and that the larger nut size isn't going to mean the ring shaft is larger and won't work with my axle housing.

[heep70]

All the same.

[ToughOldFord]

Good deal, thanks.

[ToughOldFord]

Okay, I put my 3.73s in last weekend. It looks like I've dropped about 200RPMs at highway speeds, 55-65mph
Don't know if that's enough to make a difference, but I got to wrench on my truck anyway. It went pretty smoothly too, can't complain.
Scored a 390 for $80 when I was at the wrecking yard getting my new gears so I just gave myself more to do.

[heep70]

Excellent!