Grand national 8.5 10 bolt value

79 malibuls

Not-quite-so-new-guy
Thread starter
Jun 2, 2021
17
3
Rushville Ohio
Hi all, this is my first post and hope it’s in the right stop, but.... my question is I’m looking at a rear end that is a 8.5 10 bolt that came out of a grand national. I’m just not sure of the value of it with and without a posi unit. They are wanting $1500 and it’s supposedly a posi with 3.42 gears. Any help as to the value of these rears would be much appreciated. Thx
 

87National

Master Mechanic
Apr 15, 2009
450
63
eastern SD
Hi all, this is my first post and hope it’s in the right stop, but.... my question is I’m looking at a rear end that is a 8.5 10 bolt that came out of a grand national. I’m just not sure of the value of it with and without a posi unit. They are wanting $1500 and it’s supposedly a posi with 3.42 gears. Any help as to the value of these rears would be much appreciated. Thx
$1500 is right around market value......If you are confident that it doesn't need anything, I would offer $1300. Quick Performance 9" would be a good choice for a few hundred more.
 
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L92 OLDS

Comic Book Super Hero
Mar 30, 2012
2,564
113
West Michigan
I got $1500 for the last 8.5” I sold. It lasted exactly 6 hours on craigslist. I would buy it before it’s gone. The housing on mine was not pitted and it was posi traction with 3.73 gears. I don’t understand the logic of “it’s a 40-year-old part so I’m not going to pay that much”. Rear axles are steel guys and don’t have a shelf life. You should still inspect it and ask the right questions. If it lived under a drag car all of its life that would be a different story. Go get it and be happy that you have a nice, stout GM rear under your Malibu.

BTW, if you have a 2004R or TH400 I have (4) drive shafts from VIN 9 cars I would sell. Have fun with your purchase!
 
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Ribbedroof

"That wagon guy"
Supporting Member
Jan 4, 2009
4,106
113
Wellston, OK
My comment about age (OK, 34 at the oldest) was intended to make the point that if it's out of the car, you know nothing about the life it had. Maybe it did live under a drag car, maybe it didn't.

I would wager that a 12 bolt under a truck led an easier life than an 8.5 under a car that are famous for being leaned on.

Age has nothing to do with price, don't know where that came from?

As stated in my first response, if it's worth that to YOU, go for it.

Well, gotta go drive my shitty 7.5 to work
 

69hurstolds

Geezer
Supporting Member
Jan 2, 2006
5,420
113
I agree with L92 Olds on this. But I do understand the concerns brought up about used parts and questionable pasts. But what if you buy a whole car? You're doing the same thing. I got three 8.5 rears under my cars and they're originals. Old as dirt. But yet, I have no problem running them.

Do the due diligence on checking the rear end out first just as you would check out the rest of a car if you bought one. Ask if you can bring a magnetic base dial indicator to measure some backlash and check out the axles. If you don't have a dial indicator, go by feel. It should clunk back and forth just a bit, but if it feels real sloppy, you know you'll have to fix that. If they won't let you pop the cover, then ask why. I'd see that as a sign to walk. And if you find it needs rebuilding, use that as a negotiating point.

BTW, you can get new gears and install them for probably <300 with new bearings all around. You STILL can likely get away with less than 2K into it even if you refurbish it.
 
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bracketchev1221

G-Body Guru
Jan 18, 2018
967
93
Like was said, I would make an offer you are comfortable with, change the gear oil and run it. Whatever happens after that, just go with it. I have a 8.5 housing that I have $350 into and its got no parts in it. I got it cheap because it was missing the brackets. So I had to pay my welder friend to put the brackets on and square it up.
 

ssn696

Living in the Past
Supporting Member
Jul 19, 2009
4,992
113
Permanent Temporary
Ultimately, this is about the housing. Everything else is replaceable. Even the axle shafts.

It will be hard to tell if the axle tubes are bent, but look for differences in the surface on either side of the central casting. If you spin the yoke, do both axle ends spin without wobble? Make sure there is no leak where the tubes go into the casting.

Ask for a look inside and see how cooked the fluid is. Is there a lot of shiny stuff on the ‘donut’ magnet?

Bring $1500 in cash but don’t show it until you make the deal. Make your offer. Be ready to take it home if it looks decent.
 

ck80

Comic Book Super Hero
Feb 18, 2014
2,543
113
My comment about age (OK, 34 at the oldest) was intended to make the point that if it's out of the car, you know nothing about the life it had. Maybe it did live under a drag car, maybe it didn't.

I would wager that a 12 bolt under a truck led an easier life than an 8.5 under a car that are famous for being leaned on.

Age has nothing to do with price, don't know where that came from?

As stated in my first response, if it's worth that to YOU, go for it.

Well, gotta go drive my shitty 7.5 to work
Doubt my truck :ROFLMAO:

Many buick turbo cars lived 1/4 mile at a time... my truck lived about 1/8 mile at a time, just not on pavement...but has still recently turned 90k miles.

When I think of some of the loads it's hauled. It lived the Carolina squat before it was popular. Nice thing about old trucks... they might be rated for a 1500lb payload, but they'll haul 3k in that 8 foot bed with ease. Too bad gm dropped to the 10 bolt in the 80s with the gov bomb err lock.
 

PBGBodyFan

G-Body Guru
Supporting Member
Mar 3, 2009
596
93
Wisconsin
Supply/demand, they don't make 8.5" g-body rears anymore and more and more people want stronger rears. The Ford 9" is stronger(and saps more power) but 99% of people don't need anything more than the 8.5" and honestly probably 80% of the cars are fine with a 7.5" still in it. My choice is the bolt in 8.5" over the other options and I've been lucky to find two posi rears for cheap to dirt cheap prices. $1,500 seems about right for a posi unit that is in good shape, if good enough to bolt in and not worry about anything. If you don't buy it someone else will, chances are the seller knows this.
 

64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
3,117
113
Upstate NY
It's the going price unfortunately. I'd say count on it needing clutches and bearings, but I'm quite pessimistic as well. You are taking a risk though, it could need clutches, gears, side & spider gears, axles and brakes.

But, as long as it isn't bent, then it will hold it's value if you find it's a basket case.
 

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