All, I have seen several variations of this question asked but haven't found it specifically for my application: I'd like to swap my 3.07 open differential out of a 1967 Riviera for a 3.42 posi from a 1967 Riviera (this car is not a GS, but it seems to have the posi option, either from the factory? or done after purchase? I think I was able to post pictures of the unit here; please confirm that this is an actual GM installed posi unit). Does anyone know what I will need to take from the 3.42 posi'ed car? the posi unit, the gears...do I need the carrier, the axles? Thanks so much for your help.
The carrier and gears are all you need from the donor housing; can't hurt to keep the carrier shims too. Realize you'll still need to check pinion depth, backlash and carrier bearing preload when the new carrier goes in your old housing due to machining tolerances between the two assemblies. Devon
DaWildCat, Thanks for the post. What is your opinion of the posted pictures? Does it look like a legit original GM factory posi unit? Regards.
Since the Riv it came out of isn't a GS, it's possible it could be a 3.07 also. Maybe you know for sure it's a 3.42 I don't know, I'm just making mention of it. :TU: My '66 Riv was a non GS and had a 3.07 Posi in it.
He's good to go; you can make out the 41-12 stamp on the ring gear in the photos. Getting rare as rocking horse poo! Devon
12 and 41; the teeth were counted also. I tried to confirm based on the stamping on the parts but couldn't find the numbers anywhere to confirm; is that a lost art? is there an index for part numbers somewhere? Thanks guys.
You'd have to get your hands on a Buick parts book. You can find them on CD on ebay. There's more good discussion on the 9-3/8" rear here: http://www.v8buick.com/showthread.php?t=71740 Devon
Here is a newb comment: I honestly thought they it was 8.2"; not 9 3/8s...guess I was wrong. Thanks for the link.
> part number on ring gear is 1383525*** 41-12 GMC > part number on pinion is***** 1375350** 12-41 GM > posi unit**************************** EO-32121** 228
You will not find the individual part numbers for the ring or pinion gears listed in a Buick parts book. What you will find are part numbers for gear SETS as the gears were not sold individually but in matched sets. Also, Buick changed to a larger carrier bearing on one side of the carrier sometime in `66. The axle housing is different. Take a close look and compare the carrier bearings. Honestly, if I was doing this swap, I would change the entire axle over. Then you will not need to set everything up. Good luck, Tom Mooney
yES PLEASE DO CHECK THAT CARRIER AS WILDCAT GS said the 1966 carrier is different and I also have a Casting number different than you on your carrier I have 32085 for the posi carrier. Check the carrier bearings as they will be 2 different inner diameter. YOU CAN NOT use the equal /same carrier bearing unit in a unequal size housing. Let us know as I am accumulating part numbers also . Jim
new question: can I swap my 3.07 gears with the 3.42 gears on the posi unit? will the ring and pinion interchange?
Unfortunately, no. The 3.42:1 and numerically higher carrier places the ring gear closer to the pinion centerline than the 3.07 carrier. To swap back & forth the carriers will have to be swapped along with their respective carrier bearing shims. Devon
Devon thanks. do you know if the 3.07 posi from other models and others years would fit in my '67 riv? i think i see one from a '65 lesabre offered? phil ---------- Post added at 11:11 PM ---------- Previous post was at 11:11 PM ---------- Devon thanks. do you know if the 3.07 posi from other models and others years would fit in my '67 riv? i think i see one from a '65 lesabre offered? phil
