Guys, how long are the ones we use for a '78 g-body? Where have you found them, how much have you paid? Have you bought parts/internals separate and then bought a bare axle housing, etc? Saw an add for a GN 342 posi gear set-up that he says is rebuilt for $450/best offer... Or are guys better off just saving and buying new? Thanks
Grand Natl rear end questions
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How long? All 78-88 GM Gbody rear ends are the same width. The 8.5 only requires a 1-1.5" shorter driveshaft than the 7.5 or 7.625. I call bullshit on the rebuilt 8.5 for only $450. Either the guy is lying, thinks his 7.5 is an 8.5 or has no idea what he has and what they go for. A non rebuilt 8.5 from a GN with an open carrier warrants more than that.
This is an interesting subject that people often do not agree on. Some say that if you watch Craiglist you can pick a complete 8.5" rear up for $400 - $600. I find this amusing... I partially agree with this though having sold a crusty 8.5 for $450. The value was in the housing and gear set. Everything else needed to be replaced at additional cost. Even the housing was questionable in my mind due to the amount of rust.
From what I have seen, a clean, rebuilt 8.5" rear can easily cost as much as $1,200 or more if it is complete, ready to install and has a posi carrier. I have seen price tags at shows upwards of $1,600. This might seem like a lot until you price out what it costs to build a Ford 9" for a G body. In my area if you can find a good clean 8.5" ready to go for under $1,000 you are doing good. Remember, the GN was only one car that came with the 8.5. A larger portion of them were put in T types, Hurst Olds' and 442's. The 442 and H/0 version came with the 3.73 gears so in my opinion would be a better choice anyway. Good luck with your search.
From what I have seen, a clean, rebuilt 8.5" rear can easily cost as much as $1,200 or more if it is complete, ready to install and has a posi carrier. I have seen price tags at shows upwards of $1,600. This might seem like a lot until you price out what it costs to build a Ford 9" for a G body. In my area if you can find a good clean 8.5" ready to go for under $1,000 you are doing good. Remember, the GN was only one car that came with the 8.5. A larger portion of them were put in T types, Hurst Olds' and 442's. The 442 and H/0 version came with the 3.73 gears so in my opinion would be a better choice anyway. Good luck with your search.
It sounds like the $450 is just for the rebuilt posi unit and gear set up and the OP is looking to possibly buy a bare housing to install it in.
Geo's66 said:
Primarily cost. The 8.5" GM rear end is a stout unit and can take some serious abuse. 8.5's typically cost less than a Ford 9" unless you have some serious fabrication skills and are willing to do the homework. Spend some time on turbobuick.com and you'll see some very high HP cars running 8.5 rears. Although my car is highly modified, I like the fact that it has an 8.5 and is original equipment. A 9" would likely weigh more and only be necessary if I was running 800 plus HP.
I found mine here on the Forum. Have your $$$ ready and know how to execute a PM. If you're lucky, the buyer is willing to put in on a pallet and take it to a trucking depot for you. Shipping can run $350 depending upon how far it has to go.
I'd like to see a company make a GNX-type rear cover kit with mounts to install a panhard bar/Watts link and torque arm. The GNX got an added crossmember for the front to the torque arm, and lost the rear upper control arms. 10-bolt X-body axles could be suddenly very useful...
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