8.5 rear swap

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Mar 12, 2010 | 03:53 PM

SierraSR25

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Junior Member

Joined: Apr 2009

Posts: 5

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Car: 1988 Firebird

Engine: 355

Transmission: T-5

Axle/Gears: Moser axles, 342 gears

8.5 rear swap

I have a stock 7.5 rear in my 88 firebird that is close to the end of its life. I'm takin the car off the road so i can do whatever i want to it for the track. What would be involved in swapping an 8.5 rear other than ladder bars and weldin new brackets on? Any tips? thanks

Mar 12, 2010 | 07:21 PM

big gear head

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Joined: Sep 2008

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Re: 8.5 rear swap

Ladder bars should do it. Removing the spring perches, shock mounts and panard bar brackets and welding them on the new rear end will make the installation easier.

Mar 13, 2010 | 05:56 PM

SierraSR25

Thread Starter

Junior Member

Joined: Apr 2009

Posts: 5

Likes: 0

Car: 1988 Firebird

Engine: 355

Transmission: T-5

Axle/Gears: Moser axles, 342 gears

Re: 8.5 rear swap

Do i need to put a full frame in the car to weld a crossmember to for the ladder bars?

Mar 14, 2010 | 01:47 PM

AlkyIROC

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Joined: Jul 1999

Posts: 17,274

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From: 51°N 114°W, 3500'

Car: 87 IROC L98

Engine: 588 Alcohol BBC

Transmission: Powerglide

Axle/Gears: Ford 9"/31 spline spool/4.86

Re: 8.5 rear swap

The crossmember needs to be attached firmly to something. It's possible to plate the rocker panels and weld a crossmember directly to them. Years ago when I had ladder bars, I welded the crossmember between the custom made SFC.