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Old 11-01-2009, 10:39 AM
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81 chevy 10 bolt to 72 chevy 12 bolt

i have a 81 chevy with a 10bolt rearend that i think has a 3.08 gear in it and i want to put a 72 12bolt that i think has a 3.73 gear in my truck.

i want to know if the axle shafts are the same i dont want to run a 6 lug wheel in the back and a 5 lug wheel in the front.

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Old 11-01-2009, 11:58 AM
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not likely as they are different types of rear ends
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Old 11-01-2009, 02:09 PM
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they are the same shafts

just because its a different axle model does not mean they differ



70 and up are same 12 and 10 bolt both

reaosn why only 70 and up is because in 70 the axles went 1.5" wider than 69 older

anything '71 up is 5 lug anyways, unless its 4x4

same shafts length and spline regardless though

make sure the 72 is G70 leaf type rear and not coil

because most chevy pickups were coil through 72

also most 70 and up were 3.07 because of the way more commonly ordered 350 and auto trans combos in the trucks(per GM info)

most '69 older were 3.73 and manual trans

check the ratio in the '72


anything else you need to know about the trucks let me know

Last edited by fast68; 11-01-2009 at 02:27 PM.
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Old 11-01-2009, 02:52 PM
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Quote:
Originally Posted by fast68
they are the same shafts

just because its a different axle model does not mean they differ



70 and up are same 12 and 10 bolt both

reaosn why only 70 and up is because in 70 the axles went 1.5" wider than 69 older

anything '71 up is 5 lug anyways, unless its 4x4

same shafts length and spline regardless though

make sure the 72 is G70 leaf type rear and not coil

because most chevy pickups were coil through 72

also most 70 and up were 3.07 because of the way more commonly ordered 350 and auto trans combos in the trucks(per GM info)

most '69 older were 3.73 and manual trans

check the ratio in the '72


anything else you need to know about the trucks let me know
Axle splines are not the same! 12 bolt is 30 spline and that year 10 bolt is 28 spline. The 10 bolt did not go to the 30 spline till 1989.
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Old 11-01-2009, 02:59 PM
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Quote:
Originally Posted by campracing
i have a 81 chevy with a 10bolt rearend that i think has a 3.08 gear in it and i want to put a 72 12bolt that i think has a 3.73 gear in my truck.

i want to know if the axle shafts are the same i dont want to run a 6 lug wheel in the back and a 5 lug wheel in the front.
If you send me a pm to remind me, I will look and see if I can get you a axle part number in the morning. For some reason it seems like I've done that swap before.
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Old 11-01-2009, 03:14 PM
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thanks for the replys

the 72 is a 6 lug and was a manual truck and yes it has coil spring. I know i am going to have to reweld leaf spring and shock perches.

i am planing on running stock truck rallys and i have a set of 5 lug and 6 lug wheels but if i ever get a set of aftermarket wheels i did not want to have to buy two diff lug patterns
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Old 11-02-2009, 09:13 AM
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Quote:
Originally Posted by campracing
i have a 81 chevy with a 10bolt rearend that i think has a 3.08 gear in it and i want to put a 72 12bolt that i think has a 3.73 gear in my truck.

i want to know if the axle shafts are the same i dont want to run a 6 lug wheel in the back and a 5 lug wheel in the front.
GM part#14071751 or Superior/Foot part# 5569.

That's a 30 spline 5 lug axle for your 12 Bolt. Or if your gonna hunt the bone yards,look for a 1970 & newer 2 wheel drive 12 bolt axle.
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Old 11-02-2009, 10:14 AM
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If you weren't so far away, I'd have you make an offer on the pair I have on the shop floor to take them off my hands.

And as for the information posted by fast68 I view his information as BAD, it's only my opinion take it or leave it.

I checked my references and find similar information to Prostreet6t9.
The 8.5 inch axleshafts were 28 spline with 4WD length being 31-5/16" and 2WD length of 31-3/8". Hollander Interchange numbers 1300 and 1204.
The 8.875 axleshafts were 30 spline and 4WD lengths were 31-9/32" and 2WD shafts were 31-5/16". Hollander numbers 1063 and 1062.

NONE of the spider gear sets interchange to swap a 12 and 10 bolt axle housings' shafts between the two. You can buy the later 8.5 spider gear set and swap it into the older axle to upgrade the shafts, same as the 7.5 inch GM axles. As long as you get the correct length axleshaft in the correct splin count to do so.

Last edited by M&M CUSTOM; 11-02-2009 at 05:39 PM.
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