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The Eaton Detroit Truetrac Differential (Part #913A315) is a high-performance, helical-gear limited-slip differential designed for GM 8.875-inch (12-bolt) axles with 30-spline shafts and 3.73 & up gear ratios. Built for strength and reliability, the Truetrac provides automatic, smooth torque transfer to the wheel with the most traction—improving control, stability, and performance both on and off the road.
With no clutches or wearable components, the Truetrac operates quietly and maintenance-free. Its proven all-gear design makes it an excellent upgrade for muscle cars, performance street vehicles, and off-road trucks seeking improved traction without sacrificing drivability.
Note: Eaton differentials for GM 8.5", 8.6", and 8.875" axles require special bearings.
Vehicles with small bearing bores (2.89" race O.D.), typically pre-1999: use bearing LM102949 and race LM102911.
Vehicles with large bearing bores (3.06" race O.D.), typically 1999 and later: use bearing LM603049 and race LM603012.
Features:
Helical-gear, torque-biasing limited-slip design for smooth, automatic engagement
Maintenance-free operation—no clutch packs or friction modifiers required
Durable, all-gear construction for superior strength and longevity
Enhances traction and handling under acceleration or on uneven terrain
Optimized for GM 8.875" 12-bolt axles, 30-spline shafts, and 3.73 & up ratios
Ideal for street, performance, and off-road applications
| Specification | Detail |
|---|---|
| Part Number | 913A315 |
| Differential Type | Limited Slip (LSD) |
| Axle Model | GM 8.875" (12-Bolt) |
| Spline Count | 30 |
| Ring Gear Ratio | 3.73 & Up |
| Ring Gear Size | 8.875 in |
| Axle Shaft Diameter | 1.3 in |
| Weight | 24 lb |
| Bearing Note | Special bearings required (see catalog notes) |
Fitment:
Compatible with GM 8.875-inch (12-bolt) rear axles used in various passenger cars, muscle cars, and trucks.
Ideal Usage:
On Road: Street & Muscle, Drag Racing, Circle Track, Restoration, Work Truck / Towing
Off-Road: Light Trail, Rock Crawl, Sand Sports, Extreme Off-Road, Work Truck / Towing
We are open Monday-Friday from 8am-6pm EST
Yes, customers located in and around the the Piedmont area are welcome to pick up their items from our retail location during normal business hours. Our address is:
Elite Race Fab
1514 Holbrook St Suite D-F
Greensboro, NC 27403
Elite Race Fab offers free ground shipping & handling to our retail customers within the lower 48 contiguous United States on most orders totaling $159.99 and higher, when the item being purchased is not a Freight/LTL item! Orders under $159.99 will be subject to a nominal $13.99 Flat shipping charge. Some exceptions and/or exclusions apply, in those scenarios you will be advised of any additional charges in the item details/description stating shipping exclussions/freight shipping required etc.
In regards to expedited and international shipping each order will need to be quoted on a case by case basis. You can obtain a quote two ways:
- From your shopping cart select "Request a Quote" prior to placing your order. We will review your proposed order and promptly respond with shipping estimates.
- Complete your order ahead of time indicating either expedited or international shipping during the checkout process. We will promptly determine shipping rates for your order and email you for approval and additional payment.
-Give us a call and we can ensure your item is shipped right then, to ensure you have it in time for your deadline.
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