Rear end upgrade?

[jdw]

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.

[cdowns]

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

[67 chevelle]

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

[Lee H]

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 $$$.

[airdale94]

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.

[jdw]

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.

[Lee H]

Don't have a link. 3.73s seem to be the consensus for an OD transmission.