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Old 04-16-2014, 03:07 PM   #1
jdw
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Rear end upgrade?

I've got a 1972 gm 12 bolt truck rear diff with 3.07 posi: CS10-CE10 3.07P.
Can the gearing be switched out for 3.73 posi and handle 355hp or do I need a new rear end? I'd have a shop do this. If it's doable, any recommendations on what i'm going to need to purchase?
Thanks.
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Old 04-16-2014, 05:58 PM   #2
cdowns
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Re: Rear end upgrade?

yes it can b done easily by a shop// a new posi carrier a gear set shims and bearings the whole thing can b done up and installed for you for about 1200-1400
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Old 04-16-2014, 07:03 PM   #3
67 chevelle
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Re: Rear end upgrade?

Yes , if you wanted 411s no , you would also have to change the carrier , but since you are staying with a 3 series you can use your old posi unit
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Old 04-16-2014, 07:43 PM   #4
Lee H
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Re: Rear end upgrade?

Up grade your current rear end, it's more than strong enough to handle all you can through at it, unless your making huge HP and running slicks. 3.08 uses a series 3 carrier, 3.73 uses a series 4 carrier.

However, they are now making a 3.73 gear set that will work with a series 3 carrier. Your rear end shop will be able to order the correct set and save you some $$$.
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Old 04-16-2014, 08:29 PM   #5
airdale94
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Re: Rear end upgrade?

3.73 are pretty low you'll be turning about 3,000 RPMs at 60 MPH. Unless it's a street cruiser or you have OD trans. I wouldn't go over 3.42.
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Old 04-16-2014, 09:18 PM   #6
jdw
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Re: Rear end upgrade?

I've got a tired old th350c (was to excited to see the plug when I bought it) with too low a stall on the torque converter for the new motor. Trans and converter have to go. I'm trying to figure out my options. If the cost of ultimately swapping to an O/D trans is worth it, I'm going in that direction. I really don't know a whole lot about rear diffs, so I'm trying to figure out what I'm getting into. I imagine 3.42 being too low on an overdrive in the mountains? I do have a series 3 carrier, Lee, do you have a link to any info on the 3.73s for these?
Thanks again guys for all the input so far. A shop will be doing all the work that I can't do myself. I just want to get it on the road.
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Old 04-16-2014, 09:52 PM   #7
Lee H
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Re: Rear end upgrade?

Don't have a link. 3.73s seem to be the consensus for an OD transmission.
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1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components.

My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703
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