The Stovebolt Site Forums The Shop Area Engine Shop What Rear End is this

Ok guys, I finally got my hands on a project 65' C-10. I'll soon begin the long satisfying endeavor of Prostoring it. My first hurdle seems to be what rear end I have (I don't think it's a 65' as the front is a 6 bolt and the rear is an 8 bolt.

I've included some photos to maybe help out. On is of some type of "modification" that I can't figure out why the PO would have needed for a 230.

The big question once I identify it is can I upgrade it to a posi that is going to perform behind a 410 hp 350 with a turbo 350 transmission. If not, what aftermarket should I go after?

Any help will be greatly appreciated.

http://img.photobucket.com/albums/v486/TimberDawg/P8150004.jpg

http://img.photobucket.com/albums/v486/TimberDawg/P8150006.jpg

http://img.photobucket.com/albums/v486/TimberDawg/P8150003.jpg

looks like a regular GM rear from a 3/4 or 1 ton, before the mid 70's is my guess.
While it should hold up fine, it is nothing out of the ordinary.

lets see what the experts say...

Grigg

It looks like an Eaton. Does the "pumpkin" have bolts around the front side that holds it to the housing? Some Eatons came as lockers, did you check to see if it was an open diff or not?
Scott

That looks like a HO72 3/4 ton rear, same as in 55 2nd series truck I have.

Here are some pictures of the front of the housing. It does have an open differential.

http://img.photobucket.com/albums/v486/TimberDawg/P8180003.jpg

http://img.photobucket.com/albums/v486/TimberDawg/P8180002.jpg

http://img.photobucket.com/albums/v486/TimberDawg/P8180001.jpg

TimberDawg,

That is an "Eaton" axle. GM outsourced axle manufacture to Eaton for their 3/4 and 1 tons from early on (46 maybe) up untill 1972. It is a super strong, "full floater", "removable 3'rd member", axle. Only problem is you can't get new gears for it.

The back cover plate is upside down. You need more lubricant in that axle as it lubes the bearings!

It will either be a H052 (3/4 ton) or H072 (1 ton). Only difference is in the brake drums and the gear set. It looks like a H052 to me with the smaller drum. As yours is coil spring that also points to H052. That means you PROBABLY have the 4.11 rear gear. They also made 5.13 and 4.56 (common). I've heard of a 3.90 (scarce as hens teeth), and a 3.38 (or something similar... I think this is a myth). Also heard of a 6.17, but I think that person confused this gear set with the Eaton H150 axle which is MUCH bigger.

So this axle will withstand a lot of power. It is reasonably light. However, you'll likely have to put up with whatever gears are already in it.

You can put a 14 bolt detroit locker inside the pumpkin. This is the strongest locker (or posi if you like) that you can get a hold of. Of course you can weld your spiders into a Lincoln locker if you prefer. If you get a 14 bolt locker, you'll have to buy correct length, 35 spline, 14 bolt axle shafts. You can buy some strong alloy axle shafts. You will have to bore the inside of the axle housing slightly to accept the new axle shafts. The 14 bolt axle flanges will bolt up to the Eaton hub perfectly.

This is a bullet proof setup.

New hub bearings / seals and new pinion bearings and seals will set you back a lot. Add to that the cost of a locker and new axles and it might be cheaper to buy yourself a 9" FxRD axle. Then you can get whatever gear set you want.

I have a 17 spline locker that will fit your axles, that I'll trade for a 3.90, 3.38, or 6.17 3'rd member if anyone has one and is willing to trade!

Jhaa_lives, a lot of great information in your post!

I must point out that timberdawg's rear cover is not upside down. It is installed correctly. The HO52 under my '67 has never, ever been apart since the truck was new and it is exactly in the same position as timberdawg's.

If the oil filler plug was positioned at the top of the cover, the rear end would be way, way overfilled. Oil would be pouring out the axle tubes regardless of seals.

Again, great post.

Joe

Thanks for the information everyone. I'm thinking I go for the Detroit Locker, but I'm concerned about what kind of speed I'm going to get with the 4.11 gears. Any ideas on what it will get?

I'd prefer to stay with this rear end or another Chevy.....can't bring my self to bring a FXRD part into the mix...

TD,

I understand the desire to stay with this axle, and away from furd products. After all it's a great axle. Only problem is the gearing.

What size rear tires are you going to use? What tranny are you going to use? That will determine your speed / engine RPM for the 4.11 gear set. However, unless you get a 0.73 overdrive or really tall tires, you won't get great fuel mileage on the highway.

Have you confirmed that the axle is 4.11 ratio? If it's a 4.56 or 5.13 I suspect you won't be happy with it!

Dogris, now that you mention that... it makes sense. I'll have to re-review my shop book.

Not that this helps but it looks a lot like my axles from my 58 NAPCO 4x4. I believe they were Eaton. The shape and open diff are the same though mine is a 1/2 ton.

I am going to stay with 16" tires and plan on running either a Turbo 350 or 700R4 tranny. I did confirm that it's a 4.11.

Looks like Eaton H052 3/4 ton differential to me.

With the 411 gear you will not be happy with your top end speed but you will have great torque at low speeds.

With that kind of horsepower you might want to consider a 9" f rearend to relize all that your setup has to offer at top end.

Good luck!!!! Hobert

If you really want to change it, get a 12 bolt from a '65-'72. Or if you're concerned about top end, you can always put an overdrive tranny in. I would certainly stay wit that diff over a 9", the 9" is nowhere near as strong as that Eaton!