So I'm doing a 350 swap, and it occurred to me that with the HP and torque the new engine may be pushing (Not sure, but probably in the 350-400 HP range), the rear may not cut it. It's an '84, and though I haven't checked, I'm guessing it's the sad little 10 bolt.

So I looked around and found a 9 bolt on here i'm interested in. What do you guys think a good price would be? It's got disks and looks like it comes with the hardware, 3.27 gears, etc.

And do you guys think the 9 bolt would be good to bolt right in, or should I consider a rebuild?

 

Go with a 9-bolt, much better than the 10-bolt. I've been driving & racing on my rear for going on 15yrs now. Once the limited slip wore out, I put in a spool that I ordered from Australia. I leave the line at 4k RPM, and pull the front wheels on my launch, without even thinking twice.

Can't do that on 10 bolt....it won't last one night at the track.

 

The condition of the cones just depend on each unit.

You can check the the posi without opening it up if you want. Basically you turn one side off the ground with the other tire still on the ground. If it takes 35 ft lbs or more force (use a cheap needle torque wrench) it should be good. If it takes less you might consider a rebuild or at least check the windows in the Posi.

If you do open it the ring gear should have the gear ratio stamped on it also. So you can check that too.

A good used series 3 9 bolt diff should be worth $200 or more all day long (Junk Yard prices).

If it's got upgrades or rare gears (such as 3.45s or 3.70s) making it better could be $300-$700 or higher easily depending on the upgrades.

Main thing to remember 9 bolts are expensive when it comes to parts. You can find some stuff locally (gaskets, bearings, few 3.70 gears) in the US but the majority of it has to come over seas (variety of gears, spools, cones, carriers, spider gears, cross shafts, and etc).

Overall the 9 bolt if a very good rearend for use that is a direct drop in. I have one at home that 1 of 4 broke spider cross shafts and it still ran fine for years I only checked it after the posi stopped working cause the cones were at the end of the case. At that point I ground the cones and put some splatter welds on them to make the series 3 case a spool and bought another replacement series 3 for $50 used. It'll be going back into the car once I get my car running and break the free 10 bolt.

 

haha I don't know how much track driving I'll be doing. But I can't resist when a tool in a Honda pulls up next to me at a stop light. So, for those instances, I was figuring it'd be better to have the 9 bolt. Thanks for confiming that lol

 

I'm hoping to get it for $200, I'd probably go $300 if I had to, since I'm gonna drive to pick it up. It's got the 3.27's, so that won't raise the price. And upgrading from my 2.73's I'll be happy to stick with the 3.27's I think