I've got a T56 and a mildly cammed 350. It's putting out right around 300hp to the wheels. Not an obscene amount by any means, but with the manual, I figure it MIGHT be enough to break a 10-bolt. I've got my old open rear 2.73 drum rear 10-bolt in the backyard. It's got the 28-spline axles. I can rip the brakes off, and buy ebmiller's adapter plates for my PBR brakes and bolt those to it. And then I can put a posi carrier and 3.73's in it. I'd like to go to 4.10's, but I dont want to break those. How much would it cost for all the parts I need to do this? I'm thinking gears will be $50, posi will be $100-$150 if I go used (is that a bad idea? Seems iffy to me...) and ebmiller's brackets are probably around $100 shipped. So that's $300 not including all the shims and spacers I need... do I need new bearings too probably? I've also got my current 3.27 posi 9-bolt in the car with the PBR brakes on it. I can spend around $200 on gears and and another $200 or so on a rebuild kit for it and throw it together. But the parts are SO expensive for this thing... And what alarms me is I ahve a very odd clicking/tapping/knocking noise coming from the rear axle when it goes around a corner. It's very quiet and I never hear it unless I'm rolling the car around with the engine off, but I dont know what it could be. I figure it must be a bearing or something in there, or the posi is doing something strange. The posi does work, though. But I dont want to dump $400 into a 9-bolt if the posi is gonna fail within the year. How long do these 9-bolt posis tend to last? I know this rear has about 130k miles on it. And I dont really understand what people mean about machining the cone to get them to work again. Is this a temporary stop gap measure? Or does this really fix it for a good while? Finding a 3-series 9-bolt posi carrier is gotta be far, far harder than finding one for a 10-bolt. Just not really sure what the best way to go from here is. Ideally I'd like to find a PBR-braked 10-bolt with 3.73's in it, but third gen ten bolts are proving hard to find. I cant even find any on the classifieds here. And the last thing is... I'm not making a lot of power per se, and my goals with the car are more opentrack/autocross oriented, but I'm still making enough power and I have a manual. Breaking the 10-bolt is, I presume, a real possibility. But I gotta say, I'd MUCH rather break a 10-bolt than a 9-bolt. If I have a setup 10-bolt, I can just throw new gears on it and go... How much more likely is the 9-bolt to hold up where the 10-bolt wont really? I mean if I throw some slicks on the back, is the 9-bolt really going to fare any better? Which leads me to my other concern. If I do manage to peel a pinion gear apart on a hard launch, how bad is the damage? What needs to be replaced to "fix" the housing? Is the posi trash after that? Or is it just a matter of cleaning it a little and throwing new gears on it? I know that above 3.73 things get weaker on 10-bolts, Do you guys think I can get away with 4.10s on a 10-bolt? Or is the manual just that much harder on it? I figure if I keep it on street tires I'll probably be okay... but that's no fun at all. Who wants to handicap themselves like that? A lot of you guys have been there... What would you do? And there's no way i can afford $2k on a 9 inch or a Moser. I just dont think Im making enough power to make something like that viable.

Keep in mind this...

If a 10-bolt c-clip or axle breaks, the wheel can roll out, the axle slide out & your day is ruined, when the body drops to the ground.

If a 9-bolt axle breaks, axle stays in, wheel stays in place & you just slow down. No c-clip to break.

You can do (i think) buy a 10-bolt bolt in conversion kit, or go with an axle that already has on.

Personally? I like my 9-bolt & am glad I have it.

im not a fan of the 9 bolt,too expensive and to hard to get parts for,in my opinion i would start off with a 98-02 4th gen zexel/torsen and build from there,10 bolt parts are cheap and everywhere.if your 10 bolt has disc brakes the axles cant walk out.
9 bolts blow apart just like 10 bolts,has to do with tires and driving style.ive blown my share of ten bolts. (they dont like roll backs).the posi on the 9 bolt is lucky to live through the first set of gatorbacks on the car.(the 9 bolt was the way 20yrs and 100,000 miles ago.) now because of parts cost and availability go with somthing else.

If you are going to auto cross then I recommend a Torsen or Truetrac. You can get a used Torsen from a 4th gen. Don't bother with an Auburn, especailly a used one. If you have a rear end with 28 spline axles then you probably have the 4 bolt pattern for the brakes and may not need any adapters to put the disc brakes on it. I would use new gears because it is easier to set them up. The gears would be about $170 and the installation kit would be $96.

As for the 9 bolt, a set of 3.70 gears for it were about $170 the last time I checked. I don't remember what the price is on the installation kit, but it should be around $120. I can check if you are interested.

Well I've got drum rear brakes on my 10-bolt... are you serious that I can just bolt my calipers to them anyway?

I cant afford a new carrier, so a true-trac is pretty out of the question... I especially dont want to buy a new carrier for a 10-bolt that's just gonna break the first time I put some sticky tires on it.

Check the housing ends and see if you have 4 bolts holding the brake backing plates on. If you do then the 4th gen caliper brackets should bolt on. You can also get the Torsen diff from a 4th gen and use it in your 3rd gen rear end with your 28 spline axles.

Finding a Zexel Torsen carrier without its rear end is like finding hen's teeth. I'm having a hard enough time finding anything that isn't a damned gov-loc.

This is, of course, used. Buying a new posi carrier for a 10-bolt that's destined to fly apart at some point isnt really on my agenda.