I have a 70 Malibu with original 10 bolt, 2.73 gears. I found this out this summer when I replaced the pinion seal. The pinion seal on a 8.5 has an obviously bigger inner diameter than the 8.2. Course, there again you have to have the seal out, or have pulled the yoke. But having a 3.08 might make a difference. Let me know when you find out.
Chevy High Performance magazine has an article on 10 bolts in the May edition. They claim the later 10's are almost as strong as the 12's. The later 10's (ggod ones) are identified by the smooth round cover. The smaller 10's have the ridge on the cover.
I also thought 8.5 came out later, but like Harvey I just read the May Chev Hipo article and my conv is a May 70 production. I just don't want to have to open it up to find out. I want to order a posi unit and the 8.5 will use a rebuildable Eaton. The 8.2 will use a non-rebuildable Auburn. Not good. Also, I could drop the driveshaft, remove the pinion nut and count the splines. But I just thought someone out there could tell me a little known trick about how to tell externally by just looking.
OK guys, look on page 104 of the new Chevy High Performance (May 1999), very top picture (or pg 106 bottom picture). This is what my cover looks like with those 2 small bumps on each side of the cover. Is this an 8.2 or 8.5 10bolt? This housing is obviously for a Nova/Camaro because it does not have the knobs for the upper trailing arms. But otherwise it is the same as mine. OK, I'm waiting for the experts.
All 10-bolts in 1970 were the 8.2 version. As stated earlier, the 8.5 came out in late 72 in the Chevelle line, but was offered in the Buick Skylark, the Olds Cutlass, and some Pontiac Lemans as early as 70 and 71. I'm looking for an 8.5 housing for my 70 Chevelle and this is the info I have uncovered in my search.
The info about the cover being oval, not round refers to the B-O-P 8.2" 10 bolt which is oval and also has notches on each side of the cover. The Chevy 8.2 is round and physically looks like the 8.5 cover.
The 8.5 cover with the eyebrow (like the 12 bolts) can be found in 73-77 Cutlass, but is in fact an 8.5 10-bolt and will not work in 64-72 Chevelles.
get the axle code, I can look it up for you.
It's located on the right axle tube just to the right of the carrier, they are stamped right in the tube usualy near the top. there should be some numbers followed by 2 letters.
It looks just like an engine code.
This will tell us exactly what you have
[This message has been edited by JSL (edited 03-28-99).]
The June '98 Car Craft has an article, "The Ultimate Guide to 10 Bolts". I think the only way you are going to tell without a number or taking off the cover is to check the pinion shaft and count the splines. This guide says that most 8.2s have a cover similiar to the 12 bolt. The guide also shows the early 8.5 with a similiar cover. Also says the early 8.5s and later 8.5s do not share parts. Have A Great Chevelle Day.
Here is what I found. I pulled the pinion nut, counted 25 splines. That means 8.2.
The code on the axle housing, as best as I can tell (lots of rust, this is the original single exhaust side) is CCA 042 9P2.
So far, this is what i get from the code:
CCA--3.08 (non-posi) For a fact, it is a 3.08 non-posi.
042--42nd day of the year (Wed, Feb 11, does the 0 stand for 1970?) This fits because it is an Apr 70 built car.
9P2--I'm not sure about the 9 and P, but that's what it looks like. Could the P stand for Pontiac? I am very sure the 2 is second shift, and I base that on another rear that I bought new.
OK Jeff, it's up to you. I am sure about the CCA 042 and the 2 on the end. The only way I can be sure about the 9 & P is to sand blast this area. And then there is a chance that they might go away.
[This message has been edited by DZAUTO (edited 03-29-99).]
this is everything that I can come up with for 1970 is
37 tooth ring gear
12 tooth pinion
STD Axle 8.125 ring Gear
042- Day of year axle was built
not sure about the 9P2
if it's a p it was manufactured by Pontiac
here is the list of manufacturers
I just pulled the pinion yoke and rear cover. The pinion spline count is 25 and it is a C-clip, non posi 3.08. Guess it's a 8.125-8.2. Which is correct? Is Auburn posi the ONLY choice? What posi came in this from the factory? I cannot swear that the 9 and P are a 9 and/or P. But I really think the last one is a 2 which I really think is for 2nd shift.
ANYBODY out there have a clue about what the 9 and P are (and they may be something else, it's too hard to tell. Maybe what looks like a 9 is really a G). Anyone out there with a 1970 3.08 non-posi built Feb-Apr with similar codes? If so you should have CCA, then 3 numbers, and then 3 what? My car was delivered new in Dayton, OH. So where was it probably built?
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