12 Bolt 'O' Type
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| 'O' type posi | U-bolts on yoke | Symmetrical 12 bolt cover | 1/4 cut slugs bolt in axles |
| Ring Gear Diameter | 8.4 Olds |
| Cover Bolt Count | 12 |
| Ring Gear Bolt Count | 10 |
| Ring Gear Bolt Size | 7/16 right hand thread / aftermarket gears 7/16 left hand thread |
| Axle Spline | 28 bolt in axle 60 degree spline
31 bolt in axle (SPECIAL 67-68 SUPER DUTY OPTION) 3.42 steeper ratios |
| Pinion Spline | 27 |
| Yoke Style | U Bolt & Nut Universal Joint retention (reference picture) |
| Pinion Diameter | 1.625 <<<< AFTERMARKET GEARS ARE AVAILABLE FOR 12
BOLT OLDS (For 3 series carrier only) |
| Axle Shaft Diameter | 1.382 press on bearing |
Supported Cars
| Car | Year |
| 442 | 67-68 |
| Cutlas 442 (USA ONLY) | 69-70 |
Rebuild Kit
| Part | Part Number |
| Carrier Bearing | LM501349 28S LM603049 31S |
| Carrier Bearing (Race) | LM501314 28S LM603012 31S |
| Inner Pinion Bearing | M802048 |
| Inner Pinion Bearing (Race) | M802011 |
| Outer Pinion Bearing | 86649 |
| Outer Pinion Bearing (Race) | 86610 |
| Pinion Seal | 2043 |
Mega Axle Bearing Kit
| Part | Part Number |
| Axle Bearing 67-69 SEALED BEARING | RW507CR |
| Axle seal 67-69 INNER TUBE SEAL | 8594S |
| Axle Bearing 70 OILED BEARING | A9 or SET 9 |
| Axle seal 70 EXTERNAL SEAL | 712146 |