10 bolt rear end identification

[brianp01]

Hey guys here are few pics of the rear end on my '59 pickup. It is a 3200, but I'm not sure if it is the original rear end. I tried cleaning up the passenger side axle to find any stampings and all I found was the code: MA1 26, stamped on the left, front side of the housing, can't find anything on the axle tubes.

It's a 10 bolt, at the widest width it is 10 5/8", the pinion nut is 1 1/4". It doesn't seem to have the ears at the 4 and 8 o'clock bolts, but there are slight nubs there, not sure if that helps.

I've searched a lot of blogs and websites to find this code but haven't come up with anything yet. Anyone have any idea what rear end this is? Or what that code means?
Thanks,
Brian

[1project2many]

http://www.gmpartswiki.com/getpage?pageid=21079
It looks like the original style axle but it may not be the correct year. Original stamped code for a 1959 3.90 is listed as AF. The casting number on the removable differential case should be 3725899. But '59 is a split production year so if it's an end of run truck it may have an axle built for a 1960 which is what the MA matches. Your axle has a production date of 1/26, January 26 so it's likely made in 1960. What are the last six digits of the truck's VIN? A high number indicates later production.

Oh, and FWIW, this axle generally is not referred to as a "ten bolt."

[brianp01]

Thanks for the info! The VIN 3B59B114607. My plan is to swap a 5.3 motor in and possibly use the old rear end or the rear end that comes with the donor truck. After doing some research I've been finding conflicting answers for re-using this rear end. Would it be serviceable with a 5.3 vortec and 4L60 transmission? Or should I just use the newer one and shorten the axles to fit?

Also if its not a 10 bolt what do I call it?

Thanks again for the help.

-Brian

[1project2many]

The rear has to be able to handle the torque applied across it. If you drive gently, run with the truck unloaded, and don't do any holeshots, then it could last for years. I used a "weak" 7.5 inch rear in a '79 Monte behind a Buick 455 for many years without blowing it up. If you're going to play around and leave rubber marks or use it for carrying heavy loads then you should consider something newer so you can get replacement parts in case it breaks. I kept the stock rear in my truck but it doesn't have to work that hard.

Ten bolts are a family of axle used under cars and some trucks starting in '65. The axle cover on those axles has 10 bolts but the reference is actually to the number of ring gear bolts in the differential. I don't know of a nickname for this axle. I've heard of it called a pumpkin rear because of the shape of the differential case when removed. Or a removable differential rear.

[Wrenchbender Ret]

That rear end is pretty stout. It will work good it you are not doing burnouts or drag racing. It comes with 3.90 gear ratio in most trucks. The only higher ratio will be a 3.38 gears available after market. Although there were some with 3.38 gears from the factory, they are very rare.

[1project2many]

Option codes show a 3.70 ratio in '59. That must be a rare bird indeed.