Sure grip questions

[OleNatesOlds]

I have found what appears to be a sure grip 8.25 diff in a '77 Magnum XE in pretty good shape at the local junkyard here. It uses coil springs instead of z springs for clutch pack pre-load it appears. I suppose it's the Dana-sourced Trac Lok? I'd like to swap it out for my open diff 8.25 that I was about to put in my '69 Dart. They are both 2.45:1 ratios, so that's good for me now as I'd love the mileage with my 1-bbl /6 and A904 currently. However, in the more distant future I plan to put in a A833OD with 3.55's out back because ultimately I want to grab gears.

First, is this likely a Trac Lok and is this OE LSD rebuildable?

Second, is the carrier split for Chry. 8.25" (2.45/2.56) applicable to open AND LS diffs.

I ask these because currently Dana sells new pre-'97 27-spline Trac Loks that are rebuildable and use ALL ratios, mentioning nothing about the carrier split I have heard about. Or are these only features of modern Trak Loks? Thanks

 

[OleNatesOlds]

I think I've answered most of these questions after more research. Looking at pics, the posi in the Magnum actually seems to be an Auburn-style lsd. Idk if that's OEM or not. And from what else I've read, those are the cone/clutch mechanisms which are NOT rebuildable. Also, there is a carrier split at 2.56+ for the trac lok (and Auburn) according to most vendor sites. I guess the one I visited was misinformed... maybe?

 

[OleNatesOlds]

Ok new question: What does a carrier split actually mean? What dimension changes at that ratio? The differential case? The ring gear? The actual center housing? Or...?

 

[DusterKrazy]

This means that the 2.45 gears take a specific housing and carrier. You can't really swap another set of gears into it. You would need a 2.71 housing and carrier to swap the gears out later. The 2.71 housing and carrier will accept numerically higher gear sets.

 

[OleNatesOlds]

Seriously? That makes no sense for Chrysler to have to cast two different housings for what purpose? A small housing that accepts one, maybe two, gear ratios and then you need a bigger one for the others? If that's true I wish the guy that sold me this rear would have spoken up. I was talking all about my plans to him several times before I got it from him. I also found a 3.21 sure-grip in a van right next to the Magnum that felt tighter I had actually decided on instead so as to do only one gear swap for a kind of happy medium between 2.45 and 3.55. My OD swap is pointless now unless I put @#$%ing go kart tires on the rear! :mumum: That really pisses me off now...