62 gmc ho33?

[62jimmy]

Hi, new member here and starting to collect parts for my 62 gmc project truck. I posted this on another GMC site with no response yet, so I thought I give it a try here. I have been thinking a lot about the drivetrain combo I will use and crawled under to id the rear axle. I was expecting a Dana 44, but according to the pics in my 55-62 illustration manual it is an ho33. I am not familiar with this rear. My questions are
1. Is this a strong rear, I am planning 300-400hp ls engine?
2. Are rebuild parts available and other ratios?
3 are there any stamps on the case to help me Id the current ratio
4. Did these rears come in anything else that the pumpkin would interchange with, I seem to remember my uncles 61 409 car having a similar setup.

Any help would be great!
Thanks,
Jeremy

[Captainfab]

Welcome to the forum Jeremy

I don't have any experience with the Eaton HO32/33 with that much power. The most I had in front of one was a 300hp 327. As with any differential it's not so much the hp or tq but the tires it is turning and how well they get traction. You can likely put that much power to that differential with skinny tires and be okay. But with some wider sticky tires, you will definitely find out just how strong it is. Most of the Eaton HO32/33 differentials came with 3.90 gears. There was an option of 3.38 gears and that is the only aftermarket gear available now. You can buy bearings and seals, but that is about it. There should be a code stamped on the passenger side axle tube. The '55-'64 cars did have a similar differential but as far as I know, nothing interchanges. If it were me, I would just upgrade to a truck 12 bolt. There is a lot of aftermarket support for those. I do make trailing arm mounts if you do decide to change differentials.

[62jimmy]

Thanks for the info, after doing some searching, this was kind of the feeling I was getting, not much available. I like the 3.90 gear cause I want to run a 5 speed, but I also read somewhere that there was no posi for these axles and I want that. I really liked the idea of keeping the stock width and not having to weld the mounts, but it looks like the 12 bolt is probably the direction I will be heading. From my lurking it looks like I will be making several orders from you in the future Captain,
Thanks again,
Jeremy

[Clyde65]

If it were me, I would run it with the LSx and OD trans, but if your using a TH350/400, your gonna be loud at highway speeds.

There really isnt much parts available and what is is expensive. I would consider a 12 bolt and reweld the axle mounts.

[Pappyx3!]

Welcome Jeremy, Let's see some pics!

I'm in the process of doing the 12 bolt conversion on my 62 now. Found a used rear w/ 3:07 gear ratio. Used CaptainFab's axle perches, would highly recommend them to anyone who is doing the conversion.

As far as how that HO rear would hold up to the horsepower. My truck has a 383 stroker in it with a TH400. It stood the all the abuse my son could give it! To what Clyde65 says about being loud, at 55mph I'm taching 2800-3000 rpm's, with flowmaster 10's on it you can't hear yourself think.

[Captainfab]

The '63 to early '70 12 bolt is the same width as your Eaton HO32/33.

[62jimmy]

Originally Posted by Captainfab

The '63 to early '70 12 bolt is the same width as your Eaton HO32/33.

Interesting, I do have a 64 GMC parts truck I got thrown in with the deal. I'll have to check and see what its got under it next time I get to the storage lot. Are the weld on brackets you sell for leaf or coil spring rears. The truck I'm building is a coil rear and I want to keep that setup?
Thanks again

[62jimmy]

Originally Posted by Clyde65

If it were me, I would run it with the LSx and OD trans, but if your using a TH350/400, your gonna be loud at highway speeds.

There really isnt much parts available and what is is expensive. I would consider a 12 bolt and reweld the axle mounts.

Im wanting to run a tremec 5 speed, I actually got a smokin deal on a complete vortec crate motor for it tonight, so I guess the LS motor will have to wait for another day. Is/was there even a Posi available for the HO33??

Originally Posted by Pappyx3!

Welcome Jeremy, Let's see some pics!

I'm in the process of doing the 12 bolt conversion on my 62 now. Found a used rear w/ 3:07 gear ratio. Used CaptainFab's axle perches, would highly recommend them to anyone who is doing the conversion.

As far as how that HO rear would hold up to the horsepower. My truck has a 383 stroker in it with a TH400. It stood the all the abuse my son could give it! To what Clyde65 says about being loud, at 55mph I'm taching 2800-3000 rpm's, with flowmaster 10's on it you can't hear yourself think.

I will try to get some pics of the trucks posted, the 62 is just a roller, almost completely rustfree. It came out of texas still has its last plates on it from 1988. The guy I bought it from said he bought it for the engine because it had a 348/4speed in it. It's not much to look at now because unfortunately he shot it all in primer. The frame still has much of the original paint on it and the floors and rockers are unbelievable, don't see stuff this solid in IL very often. Don't get me wrong, its no cream puff, it has plenty of dents/dings and has been worked hard, but perfect for what I want to do. Right now I have been searching for a way to remove the primer, because I would love to run it with its original 50 year old paint.

[Captainfab]

Typically the '63+ GMC's have a Dana 44 on leaf springs. I only make trailing arm mounts, nothing for leafs.

Originally Posted by 62jimmy

Interesting, I do have a 64 GMC parts truck I got thrown in with the deal. I'll have to check and see what its got under it next time I get to the storage lot. Are the weld on brackets you sell for leaf or coil spring rears. The truck I'm building is a coil rear and I want to keep that setup?
Thanks again