Posi rearend 12bolt 1965 c10

[Classic1965]

Hi, I'm in the process of restoring a 1965 Chevy c10 longbox. It has a 12 bolt rear axle with 30 spline axles. It has 3.73 gear and I'll be running a 292 L6 with a 3 speed standard. What would be the best posi unit for this. I have a 17 spline posi from my GMC parts truck with axles, but I was told I wouldn't be happy with it. This truck will be a daily driver in the good weather and will be used to pull a trailer. Thanks

[Captainfab]

As long as the 17 spline posi unit and axles are for a truck 12 bolt and are in good usable condition, I don't know why you would be unhappy with it. If you want to stay with the 30 spline, I would suggest a Eaton posi unit.

[Classic1965]

I was told te 17 spline would bind up under tight maneuvering and shake the back end of the truck up pretty good.

[chevy_mike]

The spline of the axle shafts have nothing to do with binding. A tight posi unit, regardless of spline count, can cause this. If each side are locked together and you make a tight turn, you will cause one tire to want to hop and shake.

[MikeN]

Originally Posted by Classic1965

I was told te 17 spline would bind up under tight maneuvering and shake the back end of the truck up pretty good.

I have a very tight posi unit in my 69 Chevelle (800lb springs) because I drag race it. Once the diff fluid heats up and gets thin, it will occasionally make a popping or snapping noise when turning a very tight corner, but it's no big deal. You can hear it, but you don't feel it. And this is only in very tight quarters, when backing in and out of parking spaces, stuff like that. Never at actual driving speeds.

[Classic1965]

The unit itself is a bit odd, it doesn't have the springs in the center like a conventional posi. The hopping and shaking is what I'm worried about, which I know has nothing to do with the spline count. Would a mini spool be any good in this situation?

[Classic1965]

The 17 spline setup I have is more of a limited slip

[chevy_mike]

Limited slip shouldn't have any issues. Mini spool is basically locking to two axle together. You do not want this for a street driven vehicle. There is no slipping between the two axles.

[Classic1965]

Ok, I understand now, I'll try to get some pictures of what I have for reference

[siggyfreud]

Originally Posted by Classic1965

The 17 spline setup I have is more of a limited slip

Limited slip = Posi. Different companies used different marketing terms back then, but they're the same thing.

[Classic1965]

Here are some pictures off the components

[Captainfab]

That is a typical Eaton posi (limited slip) carrier and components. It sounds like the springs and plates are just missing. They can be setup without the springs and plates. There is a video on YouTube by Toms Differentials that shows how to set them up without the springs. If that carrier needs a new clutch pack, you might compare that cost versus a new posi unit. I would definitely run that versus a mini spool.

[Classic1965]

It didn't have springs and plates in it. I took it out of the axle myself.

[WOLFMANmike]

had a mini spool in my old 69 ss nova ... they are great for track but really bad for the street ... and a big no no DEATH TRAP in the rain or even any damp road and that was in a nova your talking in a truck no weight in the bed trucks already like to brake nose heavy i cant imagine the horror in a truck with a spool lol stick with a limited slip you will be much more happy with it . and it will be safer too

[Classic1965]

Is there anywhere that sells the springs and plates that are missing? The rest of this unit looks ok. The truck had 66000 miles on it and it had a 230 L6 in front of it

[Captainfab]

I have seen the springs and plates on ebay from time to time. I don't know if any of the differential parts suppliers may have them.

[Clyde65]

Here ya go.

https://www.ringpinion.com/b2c/Parts...=192&BrandID=7

[The Rocknrod]

I used this guy for all name brand components: http://www.quickperformance.com/GM-1...-12T_c_54.html

[Classic1965]

Will these parts fit?
http://www.ebay.com/itm/EATON-HD-PRE...9TJ14b&vxp=mtr

[Captainfab]

Yes those will work. But be aware that those are likely the 800# springs.

[Classic1965]

What grade spring would be best for a daily driver?

[Captainfab]

Those springs will work but they will make the rear of the truck a bit jerky when going around corners. I believe stock springs were 400#.

[dracko]

I went with an Eaton Truetrac and haven't looked back. It's like a posi unit but uses helical gears to engage rather than clutch plates and springs, so there's nothing to wear out. I have never noticed it during normal driving conditions but it works great when you need it.

Very simple to install.

[Palf70Step]

I did not do it myself, but I took the 3:73 out of my 64 and put in the guts from a 72 12bolt rear (3.08 in my case). They had to do some stuff to keep the original axles, so I guess mine is half and half. Whatever it is, I have not had any issues whatsoever with mine and I drive it a lot.