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rbutler 08-30-2012 08:45 AM

1972 El Camino differential ID
How do I find out which rear end I have? '72 elco 350ci 10 bolt. Is it an 8.2 or 8.5?

big gear head 08-30-2012 09:32 AM

The 8.2 has a 1 1/8 inch pinion nut and the 8.5 has a 1 1/4 inch pinion nut. The 8.5 has some square corners on the bottom of the casting in the 5 and 7 o'clock positions that can be easily seen from the rear of the car.

SSedan64 08-30-2012 11:27 AM

1 Attachment(s)
X2^^, on the 8.5" square Lugs.
Seen here >> - The 1967 Oldsmobile Cutlass and 442 Resource - GM 10-bolt Differential Technical Information
The Chevy 8.2" has an inverted V on the cover just like the 8.875" 12-Bolt.
BOP 8.2" has scalloped sides on the cover >> 8.5" rear axle

big gear head 08-30-2012 11:43 AM

You have to be carefull about judging a rear end by it's cover. The Chevy 8.2 and 8.5 covers interchange. I've got a few 8.2 rear ends right now that have 8.5 covers on them, and I know a few people who have installed 8.2 covers on their 8.5 rear ends to make them look like the 8.2.

SSedan64 08-30-2012 11:54 AM

I didn't know those 2 would interchange.:cool:
Hard to miss those Square lugs on the 8.5" tho'.

Good 7.5" vs 8.5" 10-Bolt Pic >> Dorians Diff page!

big gear head 08-30-2012 12:34 PM

Yea, but I know of at least one person who cut the lugs off. Seems like a lot of trouble. Who really cares if it looks like a 8.2 or 8.5 anyway? But it seems to matter to a few people out there.

SSedan64 08-30-2012 12:53 PM

Wow, that's a lot of effort for the Period Correct look. :sweat: It doesn't surprise me tho' what some guys will do.:rolleyes:

rbutler 09-01-2012 05:26 PM

1972 elco
Help Help According to the replies and pictures I have a 8.2 rear end. NO tabs at 5&7 o'clock. But after talking to an supplier '71 and up Elcos were 8.5.Does this sound right? :(

SSedan64 09-01-2012 05:59 PM

These years/models came with 3 different rears, if you don't have the square identifiers & Pinion Nut is 1-1/8" it's an 8.2"

big gear head 09-01-2012 07:29 PM

The 8.2 was used in Chevelles, El Caminos and Monte Carlos up to '72, so you could very well have the 8.2 rear end. I haven't seen a factory installed 8.5 rear end in a '71 or '72 El Camino.

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