7.5 to 8.5 rear

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LukeZ

G-Body Guru
Apr 24, 2015
537
323
63
Delaware
hey guys, I just need a list of parts that I need to buy in order to do a swap for my 86 SS El Camino, which has a 7.5in 2.56:1 rear, all stock.

I want to upgrade to an 8.5in, or maybe 9in, so this is what I think I need so far. I need to buy this and give t all to a shop so they can install it. If I leave anything out, please let me know.

-New driveshaft that fits a 200r4, an inch shorter (I know it's an inch shorter for the 8.5, but not sure about the 9)
-new differential casing
-new ring and pinion gears, with desired ratio
-new axle
-new control arms (I'm not really sure what control arms are. To be honest, I really have no knowledge with this stuff, I just have heard people say that I will need control arms for this)
-Not sure if I can keep my original drum brakes, or if I have to get new ones.
 

565bbchevy

Geezer
Aug 8, 2011
9,590
12,611
113
Michigan
It depends on your budget and power level as far as rearends the 8.5 can be built plenty strong but you can buy fully assembled all new 9" rearends that bolt right in with your choice of gears, carrier etc. but they are by no means cheap so you have to decide which route you will go first.
 

LukeZ

G-Body Guru
Apr 24, 2015
537
323
63
Delaware
It depends on your budget and power level as far as rearends the 8.5 can be built plenty strong but you can buy fully assembled all new 9" rearends that bolt right in with your choice of gears, carrier etc. but they are by no means cheap so you have to decide which route you will go first.
Oh, I didn't know the 9in would bolt right up. Do you know of a website where I can find that?
 

565bbchevy

Geezer
Aug 8, 2011
9,590
12,611
113
Michigan
Moser, Currie, Strange, Quick Performance just to name a few that have 9" rears for Gbody you also have options for 12 bolt rears if you want to keep it Chevy. This options are many so you need to know what you want and how much power you will have and if you intend to increase it in the future the only limit is your wallet.
 

Kiko

Master Mechanic
Apr 14, 2009
296
336
63
Ottawa, Canada
I'm in the process of changing my original factory differential (rear end) to a Chassisworks FAB9. I have already converted the GP to 4-wheel disks (Wilwood), so the flange spacing will be exactly the same (at 2.5"). Also, my GP already has coilovers and new 4-link. The 4-link bolted into the original stock location and the FAB9 meets that criteria as well. Check out the Chassisworks web site (https://www.cachassisworks.com/c-9-monte-carlo-78-87-gm-g-body.aspx) since they make a "bolt it" system for the G-Body.
 
Last edited:

Kiko

Master Mechanic
Apr 14, 2009
296
336
63
Ottawa, Canada
I fixed the link in my previous post.
 
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