How do I tell if a rear from 1970 is a 8.2 or 8.5, since they made both that year? Should I just figure on telling the diference from the inspection cover differences? Also can you put an 8.5 in a 8.2 housing. I assume not because of the different splines.

no they are not interchangable (8.2,8.5 carriers) as for what you have run the numbers or measure ring gear...hope this helps.

If the rear really is a 70, its an 8.2..didnt have the 8.5 until 72, was the replacement for the 12 bolt in most hi perf applications. Parts do not interchange between the rears. Most 8.2s have a rib in the upper part of the cover for oil travel like a 12 bolt, 8.5s are smooth except for the bump out for the ring gear.

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66/70 chevelle ss396's
69/71 camaros

The Jegs catalog, under the ring and pinions, shows that there were 8.5 starting in 70,thus an over lap between 8.2 and 8.5. Thats why I am confused. What size ring and pinion are in early 70's camaros?

I don't know if this will work or not but does anyone out there have a Chevrolet Overhual Manual for 1970 Passenger Cars. I have one for 1972 Passenger Cars, it only lists one ring size for the '72 Camaros. It does however list different ring sizes for the Chevelles, and it gives a code which is stamped on the axle tube close to the carrier. It distiquishes the ring size by the manufacture code. For example C = 8 1/8 and K = 8 7/8. This might work if someone has a '70 Chevrolet Overhual Manual.

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Bryan Shook
Burgettstown, Pa
Favorite Quote - Some people have shrinks. Some people have their garage.
www.geocities.com/motorcity/speedway/6673 (http://www.geocities.com/motorcity/speedway/6673)

what a catalog says and the real world is are two different things..take your car to any knowledgable chevy guy and he will be able to tell in 2 seconds by looking at the rear cover. My bet is if it is original then it is an 8.2. If thats the case you might as well upgrade, 8.5 camaro rears are cheap, should be able to find a 3:42 to 3:73 posi rear complete for no more than $250. Came in mid to late 70s z28s and trans ams.

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66/70 chevelle ss396's
69/71 camaros

I look at differentials every day at work at a driveline shop. I can tell you from experience that there is no way to tell an 8.2 from an 8.5 by looking at the cover. They covers will interchange and are identical. Some of the early 8.2's had the "eyebrow" like the 12 bolts, but most did not. The only true way to tell is by pulling the cover. Look at the bolt that holds the spider gear pin in the carrier. What size wrench will it take to remove the bolt? If it's a 5/16" wrench, it's an 8.5. If it takes a 1/2" wrench, it's an 8.2. Simple as that. The other way to know is to get the numbers off the axle tube, and post them on here. Someone will be able to decode it for you. Good luck, and let us know what you find out.

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70 & 1/2 RS
SB406 & M20 4spd
9" rear

70 Malibu 350/TH400

Gold member #103




[This message has been edited by Scooter (edited 11-02-99).]

Thanks for the solid info. Makes life easier.

No problem, anytime.

BTW, in 1970 the Camaro was the only car in the Chevy line to get the 8.5 diff. Some 1970 Camaro's came with the 8.2, but the 8.5 was offered in some Camaro's in 1970, but not in any other Chevy. Some of the Buick, Olds, Pontiac A bodied cars (like Chevelles) had 8.5's in them as early as 1970, but in Chevelles the 8.5 wasn't offered until late 72 & 73.

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70 & 1/2 RS
SB406 & M20 4spd
9" rear

70 Malibu 350/TH400

Gold member #103




[This message has been edited by Scooter (edited 11-05-99).]

The spider gear retainer bolt wrench size is a cool way to tell the difference. Thanks for the tip!!!

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1st&2nd GENGuy