Switching Spider Gears on 9"

[rs899]

I swore I asked this question here many months ago, but now I can't find it.

I have a 31 spline 9" chunk that I got from a boneyard with a ratio that I would like to try on my truck. My truck has the usual 28 spline axels. Is it true that I can swap out the spider gears from my trucks chunk into the junkyard (ex 31 spline) chunk and use it? Are there any perils? Are all the spider gears interchangeable with all the cases? Is it straightforward? Or, should I just keep looking for an appropriate 28 spline chunk?

Rick

[fordman]

i dont know if the spider gears can be changed or not. but i do know you can swap the gears from on to the other.

[Wes]

if both 3rd members are same type you can, I would swap all 4 side gears and pinion idlers and maybe even the pinion shaft. Mark the gears so you can put them back in the same spots.

[rs899]

Wes-

What do you mean by the same type?

The clusters in question are both 9" units.

One is the original one in my 67 F-100 (3.70) 28 spline

The junkyard one is I think a 2.75 31 spline that came from about a 1980 F-100.

Rick