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72 rear spring diff bolts

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Old Sep 6, 2015 | 06:22 PM
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Default 72 rear spring diff bolts

the 4 bolts tha hold the rear spring to the diff, what grade should they be?
the ones i removed were 3 dash meaning grade 5,
but reading on net people say use grade 8...
i'm confused....

as i'm putting a new spring on to replace my saggy one, the bolts need to be slightly longer as the spring is slightly thicker thru the middle.
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Old Sep 6, 2015 | 07:01 PM
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GM used grade 5, if you're worried, use 8's. Most important thing is to not bottom the bolt in the blind holes and crack the cover. Measure that twice!
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Old Sep 6, 2015 | 07:32 PM
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those bolts are somewhat special with a long grip but short thread
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Old Sep 6, 2015 | 08:03 PM
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Originally Posted by jnb5101
GM used grade 5, if you're worried, use 8's. Most important thing is to not bottom the bolt in the blind holes and crack the cover. Measure that twice!
For sure. I looked at mine and two of them have extra washers. However with a fiberglass spring and an extra strength rear cover, your results may vary.. Just be careful.
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Old Sep 6, 2015 | 10:05 PM
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Had to go with grade 8 bolts as grade 5 not readily available over the counter here.

Actually pulled it all apart, then realised I needed the longer bolts,
But on Saturday all the industrial supply places are closed....

Being a fitter n turner, I tend to over analyze things.... have measured multiple times already,
And will check again when I mock install....
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