is it just a gear swap or complete axel change.. im just wondering what my next project is gonna be.. if this isn't a huge money project I wanna sneak this one in before the paint job... thanks
I've never done a non posi to posi..but if I were to do one..it would be an Eaton differential and a new rear gear, races and bearings...and just to have piece of mind...new axles. The gear and axles aren't mandatory...just piece of mind.. sure, it's an extra $600 but if you're gonna do it...do it right.
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1967 Starlight black PMD Engineering 400 Auto 1968 Alpine Blue 400 4 speed 1968 Verdoro Green 400 HO 4 speed 2013 1LE 2SS/RS Inferno Orange Camaro.
I was sort of worried about the rear end casing as well. Pontiac used a nodular casing on 3.36 and up posi. If you plan to go 3.36 or higher the non nodular casing may not be HD enough. May be easier to brake.
Jim at JD Race would be a big help to you. If you call him, tell him what you are interested in, he can give you the pros and cons. His is a big help and knows the rear end setup very good.
His info is J D Race & Restoration Muscle Car Differential Specialists 3641 Southern Road Richfield, OH 44286 330 990 8155 330 659 7117 www.jdrace.com
X2 on calling Jim!! He built me a 8.5 rear end Posi with 3.73 gearing....he knows his stuff and you cant go wrong with contacting him! Either way, he can tell you what you can do with what you have or suggest something different for you.
Since I'm new here, I was lookin back over some recent threads. Thought I'd chime in on this one. Hope ya'll don't mind.
I'm sure that most of ya'll already know this, but the stronger 8.5 rear ends out of the X-bodies, will bolt right in to the 1st gens. Will need to shorten the driveshaft slightly.
So, before I spent a lot of $ on an 8.2, I'd switch to an 8.5, unless you just wanna keep it more original. Also, the 2nd gen 8.5's will work in a 1st gen. But the spring perches must be moved in slightly. The reason I mention this is because a 2nd gen posi rear will be easier to find than one from an X-body. So, if a good one can be located for a reasonable price, it may be worth moving the perches. The 2nd gens with manual trannies usually had the performance gear ratios, like 3.23 & 3.42.
But if you can spend $3000 or so on a rear, might as well go with a 12 bolt package from one of the big name builders. Some like the 9" Ford. But I'd rather stay with a 12 bolt, for the street.
Or you might luck up and find a decent buy on a good used 12 bolt. But most guys now, know what 12 bolts are worth, and try to get all they can for 'em. Most of those we raced came out of BB SS Chevelles, back when you could buy the rear, with a 3.73 posi, for $100. Of course, you have to cut off the lower coil spring brackets and add leaf spring perches in the right places.
Then there are those who managed to score an BOP 8.2 nodular HD 4-pinion rear. Especially when it's the unique setup for the '67 with the mono springs and OEM traction bar mounts.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI
Then there are those who managed to score an BOP 8.2 nodular HD 4-pinion rear. Especially when it's the unique setup for the '67 with the mono springs and OEM traction bar mounts.
Yeah, we ran high 12's with a '68 E/SA Stocker, which had an 8.2, and homemade slappers. It worked just fine at that power level. But we put a 455 into a '68 bracket Bird and broke the pinion--oiled down the track and made the other racers mad. Never used another 8.2 in a race car. The pinion diameter is larger on the 8.5 and the 12 bolt. We never broke either one.
If building up an 8.5, you can go with a 30 spline carrier and axles, and increase the capacity of the 8.5 to deal with more torque and sticky tires and tracks. Now, if your Bird is just for show or mild street driving, with hard tires, then the 8.2 rear is plenty strong enuff. But if you plan on building a 455 +, strapping on some sticky tires, and taking it to the track, then an 8.5 upgrade may be a good idea for you. All depends on how you plan to use your Bird.
Most of those we raced came out of BB SS Chevelles, back when you could buy the rear, with a 3.73 posi, for $100. Of course, you have to cut off the lower coil spring brackets and add leaf spring perches in the right places. 
