I have a set of 3.73 gears out of my 86 Iroc-Z and I want to know if we can put them

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May 20, 2002 | 01:53 PM

KustomIroc

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Member

Joined: Aug 1999

Posts: 101

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From: Miramichi, NB, Canada

Car: 1986 Pro Street Iroc-Z

Engine: 383 Stroker

Transmission: 700R4

I have a set of 3.73 gears out of my 86 Iroc-Z and I want to know if we can put them

in my friends 87 Firebird. We both have the 7.5 rear ends but when I looked at his RPO code they said his gears that are in it now are 3.27's. The gears that I original had in my car were 3.23's. then I went to the 3.73's.

I pretty much know they will swap but I want to make sure.

Any opinions?

Thanks guys,
Jamie

May 20, 2002 | 02:13 PM

five7kid

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iTrader: (14)

Joined: Mar 2000

Posts: 43,187

Likes: 43

From: Littleton, CO USA

Car: 82 Berlinetta/57 Bel Air

Engine: L92/LQ4 (both w/4" stroke)

Transmission: 4L80E/4L80E

Axle/Gears: 12B-3.73/9"-3.89

3.27 is a 9-bolt Aussie ratio. Your gears absolutely will not bolt into it.

May 20, 2002 | 06:53 PM

88 427 Camaro

Senior Member

Joined: Jul 1999

Posts: 931

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From: Mpls, MN USA

Car: 88 Camaro

Engine: 427 BBC

Transmission: T400

Yep, the 3.27 rear is a 7.75 borg warner 9 bolt, not a 7.5 10 bolt and the gear sets are NOT interchangeable. The 9 bolt is much stronger than the 10 bolt, but also more expensive for parts. New posi carriers and gear ratios to 4.10 are now available for the 9 bolt too.

Miles
www.9bolt.com