In road racing, you get a lot of practice building rear ends. In thirty years of racing with these differentials, we had only one failure. We sheared the ring gear bolts at the Detroit Grand Prix. We feed almost 700 HP through our stock spec differentials, using stock stub axles and spindles, and have had zero failures. Our racing spec differential is absolutely the best that money can buy.

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overhaul kit

63-79 Complete Differential Overhaul Kit

$282.00

Kit includes bearings, seals, shims, LocTite, pattern paint, ring gear bolts and a gasket. There are a few extra parts in the kit (not shown), but rest assured, they are included at no extra charge!

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63-79 Differential

$2,196.00 – $2,548.00

All our differentials come with new ring and pinions, a GM cover, Timken bearings, seals, and an Eaton clutch pack. Duntov is now exclusively using the 11/41 3.73 ratio ring and pinion sets in place of the 10/37 3.70 ratio because the 11-tooth pinion is stronger and quieter than the 10-tooth. They are shipped complete with fill plug, and are guaranteed to perform perfectly under normal conditions and use for three years. Note: UPS won’t let us fill them with oil, so they are shipped with NO OIL.

Select options This product has multiple variants. The options may be chosen on the product page
Half Shaft

63-79 Half Shafts

$118.00 – $130.00

These are reconditioned GM parts. You have your choice of the later model 3 inch diameter tubes, or the early model 2 1/2 inch shafts.

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differential rear cover

63-79 Heavy Duty Rear Cover

$278.00 – $284.00

This part is not for preventative maintenance. If your stock cover is OK, don’t replace it. This thing is bullet proof, but breaking the stock rear cover is almost unheard of. The Grand Sport got along fine with an aluminum rear cover. This one weighs 20 lbs vs. the stock cover at 16. It comes with a gasket and a new breather, but if you don’t want to use your old drain plug, you need to order one of those too.

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63-79 New Loaded Posi Carrier

$598.00

This is an all new Eaton Style Posi carrier, and it is a vast improvement over the original equipment Eaton design. This carrier is loaded, meaning it is set up by the factory with new spider gears, heavy duty plates and springs and the new composite clutch pack. If you are building a differential for heavy duty applications, this is a good investment.

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half shaft flange

63-79 Offset Driveshaft U-Joint

$84.00

If you are trying to match up a small driveshaft with a large differential pinion yoke, or vice versa, this little offset U Joint will save you a big headache.

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differential rear cover

63-79 Stock Rear Cover

$156.00 – $168.00

These are selected stock covers, sandblasted and painted with Cast Blast, shipped with a gasket and breather. Some late 77’s came with 2-1/2 inch rear springs, and for those cars, select part number D048.

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63-79 Stub Axles

$198.00

These are NEW GM differential carrier axle yokes. The HD threaded units are GM part # 3872922, while the U bolt style is GM part # 14016436.

Select options This product has multiple variants. The options may be chosen on the product page