This is prob a dumb question but I need your confirmation before I buy this thing. I have a 72 gs with a 10 bolt (open Diff) and want to remove the assembly and install a 12 bolt posi. I have a line on a 12 bolt posi (complete assembly) unit out of a 72 chevelle from an auto wrecker, can someone confirm if this will fit my GS. I'm betting so but need a yeh or neh from someone on the board here. This will not be a #'s matching resto so purists please ignore me for now. thanks Gord
Some here say you need to shorten the driveshaft 1 inch when going from 10 bolt to a 12 bolt. Maybe my 69 is different. But I installed a 70 Chevelle 12 bolt and it bolted right in and driveshaft was a perfect fit. The tailshaft seal was in the same spot on the yoke. o No:
thanks guys, this diff assembly is relatively close to me so I'm buying it in the morning first thing, the wrecker said someone else called him today in the morning inquiring on it but didn't get back to him yet... so needed to make a quick decision before it was gone. The guy at the wrecking/salvage yard says it has a 331 ratio which seems like a wierd number to me but, i'm not concerned about the ratio right now. He says part # is 435-00941B. I don't know if this is just there part # or an actual chevy #? Thanks again for the advice, Gord
I have a chance to buy a 12 bolt rear end, with 331 gears (which I am thinking will work good for me) It's in a 69 Chevelle, I want to put it under my 71 Skylark. How much are you having to pay for the posi? This guy wants 350.00 for this non posi rear end, I'm wondering if it is worth it, wondering if I should pass, and hold out for a posi.
I am going to pay (gulp) :shock: $1,100 plus shipping? I've been told there are none in Canada and this one is in Mn.(still a 6 hour drive for me). This unit is suppose to be a complete housing assembly drum to drum with the posi in it. I'm not sure what a posi alone is worth for a 12 bolt but I figured I'd prob spend over $500 to do a posi in the 10 bolt and still have a 10 bolt? Good luck. If you have time to wait, someone will prob jump in here and give you a cost estimate on the posi. I have to move fast on this one because of my location. Gord
Does your 71 still have the original rear end in it? If it does then just put a posi in that. If its original then its an 8.5 corpoate rear and plenty stong plus parts are cheaper and more plentiful than for the 12 bolt. Its also got bolt in axles and not c-clips like the twelve bolt.
For the Chevy 12...your rear u-joint will need to be changed to a NEAPCO 3-3130...otherwise you can not bolt your Buick u-joint to the Chevy yoke. As for the 71-2 Skylark 8.5" open rear, get a nice used posi and have it installed and you will be set. I have an article on our site on how to locate and remove the corporate 8.5" posi units. GM used them from 71-87 so you can choose from many years.
Thanks for the advice on the u-joint George, I may have jumped the gun on buying the 12 bolt chevy assembly as it sounds like the 10 bolt would work fine, Hope I didn't make it sound like i was dishing the 10 bolt buicks.. sorry guys, Gord
Gord, until one spends the big bucks on a custom built tapered bearing bolt-in axle 12 bolt, one is better off with built up 8.5 A-body rear. I've built several that are behind high torque Pontiacs & Buicks with TKO conversions. Price differences... Last 12 bolt Chevelle rear I shipped out built with tapered bearing ends, new Moser axles, steel lh cap, & HD 3 series carrier & 3.73's totalled near $1760. Same strength 8.5 rear on an A9 bearing A-body housing with 30 spline Mosers & new 8.5 30 spline Eaton can be built for around $1100 in parts. Labor is whatever it costs you. Till steel went up, new 8.5 30 spline Eaton carriers made it even more affordable. Last, if your Buick 350 is relatively stock, you can even get by with a good 28 spline posi. Hope his helps. Got Posi? :3gears: Roger
?????????????/ None in Canada I guess my 2 spares are of value then you can find 12 Bolts for 68-72 A bodies in Canada they just are not as easy as they once were IF you do find a housing then look at spending 1500-1900 for posi, gears, and set up or you can order one from currie or even. But thats the facts in Canada they are hewre but getting hard to find Ken
