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lunchbox locker question


Well-Known Member
May 17, 2008
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City, State
Glassboro, southern jersey
Year, Model & Trim Level
1996 Limited 5.0
Im looking to pick up a spartan this week for my 96 ex and im curious as to why they cant be used in a ls rear? I havent opened up my axles that im building but with it being a D4-3:73 ratio that i pulled i can only imagine it is an ls like in my truck now. And if if it has the S clip in the center of the spider gears that would confirm that correct?

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The LS rear's carrier is different from the "open" carrier because it has provisions for the LS' clutch discs - this means that the internal dimensions of the LS carrier is different from the open carrier. And since lunchbox lockers go inside the carrier, often times, a lunchbox locker that's designed for one can not be used in another and still operate properly. However, if you're a machinist, you can probably turn a pair of spacers on a lathe and make the usual lunchbox locker work in an LS carrier.

In the image below, you can see the "ears" of the clutch discs that are sitting in the notch behind the side spider gear - an open carrier does not have provisions for these discs:

powertrax makes a lunchbox locker for ls diffs. check them out. their customer service is pretty good at answering any questions you may have as long as you have the specs of your diff on hand.

if if it has the S clip in the center of the spider gears that would confirm that correct?
Yes - the S-spring would be a positive confirmation that the carrier is a LS unit.

i appreciate the break down. Im ordering my gears friday from east coast gear supply and i mentioned gettin an aussie or powertrax and i was told im better off with the stronger spartan. but i will have to ask about the lock right for lsd. But if all else fails i suppose they offer a open carrier used for $35. Just trying to figure out the easiest route. as a matter of fact im going to go out now and pop the cover of my build axle. But while i have you here, do you guys have a preferance or experiance with aussie, powertrax, spartan? This will be a daily driven weekend warrior so i know theyll hinder streetability but not sure how much, im used to trailer queens

Since you are regearing and you have to set up the gears again (don't forget to buy a master install kit too), it really doesn't matter whether you switch over to an open carrier (and go with an Aussie or whatever) or keep the LS carrier (and go with the PowerTrax). I don't know the exact cost of each locker but the added cost of a new carrier will probably even out with the PowerTrax considering that an Aussie (and the likes) is typically a bit cheaper.

When i called yesterday i was quoted $660 for front and rear gears and master install kits, seems like a good price to me. Both the rears i have are lsd's. So when i call today ill ask about the powertrax for the lsd. between the 3 of them they range from $280-305 so not that big of a difference BUT if i have to buy the open carrier i mind as well pick up the spartan. I was told since its the newest theyve had the time to work out any bugs and build stronger than aussie/powertrax. But also concidering ill mildly be seeing rocks this summer and its mostly mud and sand, im sure theyd all hold up..... i hope. I was also planning on lincoln locking the front as well