The rear end i have has no letters on the tube like others i have. Can the castings on housing tell me anything ? year month or what ever ? thanx
So it should be an 8.5 10 bolt rear. Look for the lugs on the bottom of the pumpkin, and the rear u-joint retained by straps and 4 cap screws. (not u bolts). If you want to know the ratio, either count the driveshaft turns to one wheel revolution, or take the cover off and read the numbers on the ring gear. The casting numbers won't tell you the ratio. Probably a 3.08.
I looked and looked some more and the casting wont tell you nothing about it? the Sloan paper says it is (G4) 3.08 or 3.42 posi but is it the rear that came in the car? Or is there no way to tell that, or year. On some ring gears i have seen the date on it as well as the ratio. I'll take the cover off and let you know what i find in a few days. Thanx, Larry
I have never seen anything definitive on casting numbers. They certainly won't tell you the ratio, that's for sure. The car is 45 years old, who knows what's been done to it? The 71-2 cars got the 8.5 10 bolt, a good rear. It's easy to determine that, just look at the pumpkin and u-joint retention.
last three didgits 700 and 724 are BUICK only 1968-1970 10 bolt 8.25. The one that has the 1.875 pinion and the larger driver side carrier bearing and standard passenger side 10 bolt carrier bearing Cover will be the same as a GTO IF you have a GS rear under the car think twice before trying to remove your axle bearings for NEW they will be the RW507GR bearing and they are VERY VERY hard to get and expensive. If you have the standard skylark 8.25 rear it will have the standard RW507CR bearing like GTO and Oldsmobile rears with bolt in axles. So the next question is what are you going to DO with this rear? Gears are available custom Fabcraft gears for 575.00 a set. Posi unit for those gears are 430.00 Bearing kit 130.00 If you just have 2.73 or 2.93 ratio and want posi we have those unit also 419.00 So hope this helps you out. Hey Larry how come you did not reference the jdrace web site for those casting numbers 1382700...lol. Jim http://www.jdrace.com/diff_id/10bBOP_Buick.htm