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#1
09-04-2001, 01:23 PM
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I have a 8.5 from a 72 Skylark that now has 3.42 and the clutch type Posi.I have a chance to trade for an original ZH 68 GTO (8.2 3.55 4 pinion Posi)rear.Is the 8.5 the better of the two?Isn't the clutch type Posi the weaker of the two since the case has large openings in it?
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#2
09-04-2001, 01:23 PM
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I have a 8.5 from a 72 Skylark that now has 3.42 and the clutch type Posi.I have a chance to trade for an original ZH 68 GTO (8.2 3.55 4 pinion Posi)rear.Is the 8.5 the better of the two?Isn't the clutch type Posi the weaker of the two since the case has large openings in it?
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#3
09-04-2001, 01:30 PM
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The 8.5" is stronger. The fact that it has clutches in the posi unit just means that it can be rebuilt, unlike the cone type posi's, which cannot. Stick to the 8.5".
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#4
09-04-2001, 02:22 PM
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Dick Duclow told me that with an automatic, up to 500 horsepower is safe with the 8.2, even with slicks. It's what I run now with about 450-475 horse.
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#5
09-04-2001, 06:03 PM
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I had the cone clutches in my 8.2 posi unit machined going on 7 years now and have had no problems yet in my full wieght low 12 sec 68 GTO. I've run nothing but Red Line oil since then. I think the automatic is the key to it's long life. That said the 8.5 you have is a good rear and I think the Buick & Olds 8.5's from those years have bolt in axle retainers like the BOP 8.2. Unless your a resto freak I'd keep it.
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68 GTO,3860# Stock Original 400/M-20 Muncie,3.55’s 13.86 @ 100 Old combo: 462 10.75 CR,,SD 330CFM Round Port E's,Old Faithful cam,Jim Hand Continental,3.42's. 1968 Pontiac GTO : 11.114 @ 120.130 MPH New combo: 517 MR-1,10.8 CR,SD 350CFM E's,QFT 950/Northwind,246/252 HR,9.5” 4000 stall,3.42's 636HP/654TQ 1.452 10.603 @ 125.09 http://www.dragtimes.com/Pontiac-GTO...lip-31594.html |
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#6
09-05-2001, 12:49 AM
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Yes it does have the bolt in axles.I found the 8.5 housing in a 72 Buick,the posi in a 75 Camaro (so the c clip groove is present on the side gears but not used),and the 3.42's came from a 70's Chevy van.Hopefully it will live for awhile behind a 455 and an M-21.
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