Moser 12 Bolt with Steel Spool and 33 or 35 Spline Axles


                                     MADE THE AMERICAN WAY IN THE USA!

If you find a lower price I want to know about it! I'll match or beat any legitimate price you find´╗┐

Swaybar brackets are now included at Brute Speed´╗┐ for no charge

Two 6BLCLAMPS (brake line clamps) are now included for no charge

LCA Relocation Brackets are included for no charge

Note: This rear does not comes fully assembled, as you have to reuse your 10 bolts brake backing plates. You will have to slide your 10 bolts brake backing plates onto the axles and press the supplied wheel bearings on to the axles. 

Installation Instructions can be found at this link:

                Product will ship 2 business days following the completion of online order.

All Moser 12 Bolt Housings are designed and manufactured in the U.S.A. using Moser Engineering owned Casting Boxes.

Package includes; New Moser 12-Bolt Made in the U.S.A. Housing, with OEM located mounting provisions, seamless steel tubing (3" O.D., 1/4" wall), custom alloy axles (30, 33, or 35 spline), bearings, studs, seals, heavy duty retainer plates, new housing ends, t-bolt kit, steel spool, pinion yoke, ring & pinion, rear cover, set up with Timken bearings. It basically includes everything you need, ready to bolt-on.  You will need a u-joint, gear oil, vacuum line for the breather and two 3.00 inch exhaust clamp u bolts unless you order the rear with the sway bar brackets.

Standard Finish is no coating (bare metal), Powder Coating optional (adds 2-3 Days processing time).


Free Shipping!

Rears are shipped just two days after the rear is ordered! Please allow two extra days if you order the rear with the optional powdercoating.

Part # 5S1233-4 - 12 Chevy Bolt 33 Spline Steel Spool (4 series)

  By changing your carrier to a Moser performance spool, not only will you save weight, but you will also enhance the performance of your car. In addition to performing better, the life of your rear end will increase by reducing deflection in your case and eliminating the possibility of side gear failure.


10 Bolt, 12 Bolt and 9 inch Information
The factory 10 bolt that came in these cars has a very small 7.5" gear.  A variation of this rear was used back in the '70's in the Chevy Monza, then in the Chevy S-10.  GM had to of known they would have warranty claims when they decided to use this rear in the 3rd and 4th gen f body's, apparently the cost of creating a stronger rear was higher than what they thought the warranty cost would be.  This has been a real plus for the aftermarket, as a bone stock LS1 F Body with a manual transmission can break one of these 10 bolt rears!  Many people have tried to beef these 10 bolt rears, spending a lot of money in the process.  What they normally end up with is a rear that still breaks, as everything on these rears is too small.

The 12 bolt rears that are available for these cars is a step in the right direction.  The 12 bolts are well known for being a stout rear that was a factory option back in the day in many performance cars.  You can have a 12 bolt in an early Chevelle, Nova, Camaro, etc, and beat the snot out of it and not hurt anything.  Put a 12 bolt into a late model f body that uses a torque arm, make a couple 4000 to 5000 rpm launches at the dragstrip, and I can just about guarantee you'll have a lot more gear noise on the way home.  The torque arm seems to distort the housing on the 12 bolts, and it seems to happen to all the brands of 12 bolt rears.  This does not happen to the 9 inch rears, and there is no price difference between the 12 bolt and nine inch rears.  As the horsepower in our engines keep escalating, most people these days go straight to the nine inch rear.  The 9-inch has an internal rear-pinion support that also supports the gear end of the pinion to limit gear deflection under high torque loads.  This seems to be the major reason why the 9 inch doesn't start whining after high rpm clutch dumps, when the 12 bolt will pick up noise.  The 9-inch locates its pinion gear lower on the ring gear to improve tooth contact, better the 12 bolt does.  The 9-inch also has a 0.125-inch larger ring-gear diameter and internal pinion support than the 12 bolt.

Includes Moser 12 Bolt, differential, housing, M/E Custom Alloy Axles, wheel bearings, wheel studs, retainer plates, Pro Street gears, 1350 series pinion yoke, built in torque arm bracket and chrome cover.
  • Item #: Moser 12 Bolt with Steel Spool
  • Manufacturer: Moser Engineering
  • Condition: New
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Price $2,650.00
Sale Price $2,550.00

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